JP3759397B2 - Gear and method for manufacturing the gear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a specially shaped gear having a tooth profile with a reverse taper on an outer peripheral wall of a small-diameter portion surrounded by a rim.
[0002]
[Prior art]
The gear for an automobile transmission equipped with a reverse tapered tooth profile (dog gear) used for the synchromesh mechanism has a donut shape in which the large diameter portion and the small diameter portion overlap in two stages, and the reverse tapered tooth profile has a small diameter portion. Is formed.
As this type of gear, there are known one in which a large-diameter gear and a small-diameter gear, which are separate from each other, are integrated using electron beam welding, spline fitting means, or the like, or an integrally molded product by forging.
Gears that are integrated using beam welding need an assembly process, and there are concerns about adverse effects due to welding distortion. Gears that are integrated using spline fitting means are the same as described above. In addition to the necessity of an assembly process, a spline must be formed, and the spline formation process is complicated, so that an integrally formed product by forging is preferred.
[0003]
[Problems to be solved by the invention]
The wave of lightweight and compact automobiles extends to the gears, and in order to meet the demands, the small diameter part is submerged in the side surface of the large diameter part to reduce the thickness, and the peripheral part of the large diameter part becomes a mountain, reverse taper The so-called sinking type, in which the tooth profile is surrounded by the mountain, is becoming widespread.
Since the reverse tapered tooth profile is formed by a punch projecting from the radial direction to the central direction, the sink type gear has a low degree of sinking in the case of an integrally forged product, and between the reverse tapered tooth profile and the rim. If it is a product that is widely open, it can be molded by using a bent bowl-shaped punch that has been bent forward to get over the mountain in front, or protruding with an arcuate movement, but with a reverse tapered tooth profile Even if an attempt was made to increase the degree of sinking in order to reduce the distance from the rim or to make it thinner, it was not possible with integral forging.
[0004]
[Means for Solving the Problems]
The present invention is a gear technology that is integrally formed by forging without being united, and its configuration is a stepped donut shape in which a large diameter portion and a small diameter portion overlap each other, and a tooth profile with an inverse taper around the small diameter portion Constrain the range except the small-diameter part including the reverse tapered tooth profile and the rim-forming part in the large-diameter part continuous to the small-diameter part, A gear with a rim formed by concentrically surrounding the small-diameter portion with the extruded meat and a stepped donut shape where the large-diameter portion and the small-diameter portion overlap each other. For primary molded products with a tapered tooth profile, constrain the range except the small-diameter part including the reverse-tapered tooth profile and the rim-forming part of the large-diameter part continuous to the small-diameter part, and the peripheral edge in the large-diameter part. Push the meat of the part to the small diameter side Out, there the small-diameter portion at its extruded meat and a method of forming a rim surrounding at concentric circles.
The primary molded product is preferably provided with a raised portion having a volume corresponding to the meat to be extruded or a raised portion equal to the formed rim width on the outer peripheral surface of the large diameter portion opposite to the small diameter side. .
In addition, the tooth profile can be formed on the outer periphery of the rim portion simultaneously with the formation of the rim portion.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
A gear manufacturing method according to the present invention will be described with reference to the drawings.
FIG. 1 shows a forging device for forming a primary molded product into a product. The primary molded product 1 includes a small-diameter portion 3 with a boss portion 2 and a flange-shaped large-diameter portion as illustrated in FIG. 4 is arranged coaxially next to each other, and on the opposite side of the large-diameter portion 4 to the small-diameter portion 3 side, a raised portion 5 is provided on the outer peripheral surface, and a stepped donut with a shaft hole 6 penetrated in the center. In the shape, a reverse-tapered tooth profile 7 is formed around the small diameter portion 3.
This primary molded product can be easily obtained by a known forging device.
[0006]
The forging device includes a die 10 having a cavity 9 provided with a receiving surface 8 that supports a lower surface of the primary molded product 1 with the small-diameter portion 3 facing downward, and a clamping device disposed on the outer periphery of the die 10. An upper die 16 composed of a die case 11, a lower die 13 composed of the die 10 and a die plate 12 that supports the die case 11, a punch 14, and a punch case 15 that supports the punch 14. The punch 14 includes an outer punch 14 b that moves up and down integrally with the punch case 15, and an inner punch 14 a that can absorb the applied pressure through the urethane material 17.
[0007]
The outer punch 14b has a cylindrical shape equal to the width of the rim to be extruded into the primary molded product, and the inner punch 14a is assembled so as to be slidable up and down in the outer punch 14b. The urethane material 17 is biased to a position where the head is protruded from the outer punch 14b so that the compression can be started.
On the other hand, the receiving surface 8 formed in the cavity 9 is provided with a rim forming concave portion 18 along the peripheral edge, and a constraining concave portion 19 corresponding to a tooth shape with a reverse taper. A knockout pin 21 having a knockout sleeve 20 at the tip is provided so as to be able to protrude and retract from the bottom.
[0008]
When the primary molded product 1 is set in the cavity 9 of the lower mold 13 (a in FIG. 3) and the upper mold 16 is moved downward in the forging device formed in this way, first, the inner punch 14a is moved to the primary molded product 1 first. The inner punch 14a and the receiving surface 8 in the cavity 9 except for the small diameter portion 3 including the reverse tapered tooth profile 7 and the rim forming portion in the large diameter portion 4 continuous to the small diameter portion 3. The range is constrained (b in FIG. 3).
[0009]
At substantially the same time, the outer punch 14 b comes into contact with the raised portion 5 in the primary molded product 1 and starts to pressurize the raised portion 5.
The raised portion 5 of the primary molded product 1 is formed in a shape symmetrical to the rim so as to have a volume corresponding to the rim of a gear to be molded, and is also formed on the receiving surface 8 formed in the cavity 9. Since the rim forming concave portion 18 is provided along the peripheral edge, the meat of the raised portion 5 is moved downward by pressurization, and the peripheral meat of the large diameter portion 4 is pushed into the rim forming concave portion 18. The rim 22 is formed by the extruded meat, and the opposite surface is finished flat (c in FIG. 3).
[0010]
In the process in which the rim 22 is formed by extrusion by the outer punch, the pressure by the inner punch 14a is also acting on the primary molded product 1, but since the urethane material 17 is interposed in the inner punch 14a, the urethane material 17 No movement of the meat in the small diameter portion 3 occurs without retreating against the urging force caused by and exceeding the pressure sufficient to restrain the primary molded product 1.
The constrained portion formed by the receiving surface 8 and the inner punch 14a is formed with a reverse tapered tapered tooth profile 7. The constraining concave portion 19 is formed on the receiving surface 8, so that the constraining concave portion 19 The entire reverse tapered tooth profile 7 is guarded and the tooth surface is protected.
The constraining concave portion 19 may be a ring groove type that does not contact the reverse tapered tooth profile 7 or an internal tooth type in which the reverse tapered tooth profile 7 closely fits.
[0011]
When the rim 22 is extruded, the knockout pin 21 is pushed up to release the mold through the knockout sleeve 20 (d in FIG. 3).
If this method was used, a tall rim 22 stood around the inverted tapered tooth 7 formed around the small diameter portion 3 as shown in FIG. It becomes feasible to manufacture the sink type product 23.
[0012]
In the above embodiment, as the primary molded product, a protruding portion of a volume corresponding to the extruded meat is formed on the outer peripheral surface of the large diameter portion opposite to the small diameter side, but it is opposite to the small diameter side in the large diameter portion. Primary molding that does not have a raised portion on the side surface, or conversely, primary molding in which a small raised portion equal to the rim width to be formed is provided on the outer peripheral surface on the small diameter side in the large diameter portion As shown in FIG. 5, on the outer peripheral surface of the large-diameter portion opposite to the small-diameter side, a volume bulge portion 5 corresponding to the extruded meat is formed, and the small-diameter side outside of the large-diameter portion is formed. It is also possible to employ a primary molded product 1 ′ provided with a raised portion 24 on the peripheral surface that is equal to the rim width to be formed.
When a primary molded product that does not have a raised portion is adopted, the peripheral edge of the opposite side surface is depressed, a large-diameter boss portion is formed, and the outer peripheral surface on the small-diameter side of the large-diameter portion is formed on the formed rim width. If a primary molded product provided with an equally low raised portion is employed, an ultra-sink type can be formed even with a small amount of extrusion.
[0013]
In the embodiment, external teeth are formed on the outer periphery of the rim (large diameter portion) of the product by cutting means. However, if a tooth profile for forming external teeth is provided on the inner peripheral surface of the lower mold cavity. It is also possible to form a tooth profile simultaneously with the extrusion of the rim.
In addition to the straight tooth profile, the tooth profile can be formed as a helical tooth profile by relatively rotating the die and the primary molded product.
Furthermore, the inner punch is provided with a urethane material so as not to apply a pressing force exceeding a predetermined level, but it can be provided with an equivalent function by using a spring, a hydraulic cylinder or the like instead of the urethane material.
[0014]
【The invention's effect】
According to the present invention, by forging a primary molded product in which a reverse tapered tooth profile is formed around a small diameter portion in advance, a rim is formed around the reverse tapered tooth profile with meat extruded from the peripheral portion of the large diameter portion. Therefore, the molding of the super-sink type gear is realized.
However, when extruding the peripheral portion of the large-diameter portion to the small-diameter portion side, the range except the small-diameter portion including the reverse tapered tooth profile and the rim-forming portion in the large-diameter portion continuous to the small-diameter portion is constrained. In the process in which the reverse tapered tooth profile is protected and the rim is pushed out, the constrained portion does not deform.
As a primary molded product, if a ridge having a rim width to be formed is provided on the outer peripheral surface of the large-diameter portion opposite to the small-diameter side, the extruded rim will eventually have a height of the ridge. Since the extrusion height is added to the rim, it is advantageous for forming a super-sink type, and if the bulge part of the volume corresponding to the rim is provided on the opposite side of the small diameter part on the outer peripheral edge of the large diameter part, the rim can be There is no risk of lack of meat.
Further, if a tooth profile is formed on the outer periphery of the rim simultaneously with the formation of the rim, gear cutting is not necessary.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a molding apparatus.
FIG. 2 is an explanatory view showing the shape of a primary molded product.
FIG. 3 is an explanatory view showing a molding process.
FIG. 4 is an explanatory diagram of a product.
FIG. 5 is an explanatory view showing a modified example of a primary molded product.
[Explanation of symbols]
1, 1 '··· Primary molded product 2 ·· Boss part 3 ·· Small diameter part 4 ·· Large diameter part 5 ·· Ridge part 6 ·· Shaft hole 7 ·· Tooth profile with reverse taper, 8 · .. Receiving surface, 9 ... cavity, 10 ... die, 11 ... die case, 12 ... die plate, 13 ... lower mold, 14 ... punch, 14a ... inner punch, 14b ... outer punch, 15 .. Punch case, 16 .. Upper mold, 17 .. Urethane material, 18 .. Recessed recess, 19 .. Recessed recess, 20 .. Knockout sleeve, 21 .. Knockout pin, 22. 23 ... Product, 24 ... Raised part.

Claims (4)

 For a primary molded product with a stepped donut shape with a large diameter portion and a small diameter portion overlapped, and a tooth profile with a reverse taper formed around the small diameter portion, a small diameter portion including a reverse tapered tooth shape, and a small diameter portion A gear that forms a rim that constrains the range except the rim-forming portion in the continuous large-diameter portion, extrudes the peripheral portion of the large-diameter portion toward the small-diameter portion, and concentrically surrounds the small-diameter portion with the extruded meat Manufacturing method. The gear manufacturing method according to claim 1 , wherein the primary molded product is provided with a raised portion of a volume corresponding to extruded meat on an outer peripheral surface of the large diameter portion opposite to the small diameter side. The gear manufacturing method according to claim 1 , wherein the primary molded product is provided with a raised portion equal to a rim width to be formed on an outer peripheral surface on a small diameter side in a large diameter portion. Method for producing gear as claimed in claim 2-3 for forming a tooth profile on the outer periphery of forming simultaneously with its rim portion of the rim portion.

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