JPH04147735A - Manufacture of helical gear - Google Patents

Abstract

PURPOSE:To manufacture a helical gear by giving a torsion in the peripheral direction to the end faces on both sides of a spur gear blank having the same tooth form as a helical gear to be manufactured. CONSTITUTION:A form-rolled spur gear blank 3 having a pitch circle a module, a tooth height, etc., is heated in a high frequency heating equipment and both sides are pressed and held by discoid pressing fittings. Then, axis 1, 1' of rotation are rotated by an amount equal to the angle of torsion of the helical gear to make a helical tooth form and an error in the direction of a tooth trace is corrected by a guide die 5. As a result, a helical gear having an accurate angle of torsion can be obtained, the degree of freedom of a prescribed angle of torsion becomes large and a helical gear having an arbitrary angle of torsion can be manufactured inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a helical gear by twist forming.

(Prior art) Manufacturing of helical gears as shown in Figure 2 involves cutting the gears by machining using a gear cutting machine, or by ordinary method, rolling method or extrusion forging. The law has also been adopted.

An example of the rolling method is shown in FIG.

In Figure MS3, a disk-shaped blank 30 is rotatably supported, and a coil 32 of a high-frequency induction heating device is arranged around it. A pair of roller molds 31, 31 each having a helical tooth shape formed on the outer periphery is installed at symmetrical positions on both sides of the blank 30 so that the rotation and axis spacing can be varied. The blank 30 is heated with a high-frequency induction heating device to soften it, and is pressed against the blank 30 from the left and right while rotating the roller mold 31. Forms a helical tooth shape.

The extrusion forging method is shown in FIGS. 4 and 5.

In FIG. 4, 40 is a die in which a female helical tooth shape 41 is formed on the lower part of the inner surface of a hollow cylinder. Punch 43 guided by 42
The blank 44 is extruded and passed through the female helical tooth profile 41 to form a helical tooth profile on the outer periphery of the blank 44 to manufacture a helical gear 45.

JP-A-58-176046 proposes a method of manufacturing a combination gear of a helical gear and a spur gear using such an extrusion forging method. Further, Japanese Patent Application Laid-open No. 115341/1983 describes a helical gear forging device that sequentially forges the center hole and bevel of a gear using a knockout punch and a knockout die.

FIG. 5 shows another extrusion forging method, in which a die 50 with a female helical tooth profile 51 is supported for rotation by a guide roller 52 guided by a guide groove 53, and the die 50 is attached to the outer periphery. Punch 5 with a corresponding male helical tooth profile
5 in the direction of the arrow, punch out the blank 54 placed on the die 50 with the tip of the punch 55, and then
The female of No. 0 is extruded through the helical tooth profile 51 to produce a helical gear 56 with a helical ring formed on the outer periphery as shown by the broken line in the figure.

(Problem to be solved by the invention) When manufacturing a helical gear using the gear cutting machine, the time required for gear cutting is long and the cost is high, and the streamlines of the flank material are cut. This weakens the strength of the teeth.

In the case of the rolling method shown in FIG. 3, two roller molds each having a helical tooth profile are required, which increases the manufacturing cost of the molds.

In the case of the extrusion forging method shown in FIG. 4, the plastic deformation of the blank is large, making it difficult to manufacture gears with large modules.

In the case of the extrusion forging method shown in FIG. 5, since there is a punching step, it is difficult to manufacture large gears, and the equipment is expensive, resulting in high costs.

The present invention aims to solve the above-mentioned problems by using a blank spur gear, which is easy to manufacture, and forming it into a helical gear using an extrusion forging method.

[Means and effects for solving the problem] The present invention provides a blank that is previously manufactured in the shape of a spur gear with the same tooth profile as the helical gear to be manufactured, and presses and holds both end faces of the blank so that a circumferential direction is formed between the both end faces of the blank. A helical gear that corrects the helical tooth profile formed by twisting on the blank by imparting a twist to the blank, and then meshing and rotating the teeth of the blank with a mold in which a predetermined helical tooth profile has been formed. This is the manufacturing method.

The spur gear-shaped blank is twisted and plastically deformed between its opposite end surfaces, and the outer peripheral surface is transformed into straight teeth or helical teeth. The beveled teeth of this blank are rotated while meshing with the tooth profile of the mold having an accurate helix angle, thereby correcting the tooth helical direction error and manufacturing a helical gear having an accurate predetermined helix angle.

〔Example〕

FIG. 1 is an explanatory diagram showing the manufacturing process of an embodiment of the present invention.

Blank 3 is a spur gear that has the same pitch circle, module, tooth depth, etc. as the helical gear to be manufactured.
It is manufactured in advance by die forging, the above-mentioned rolling method, extrusion forging method, or the like.

As shown in Fig. 1 (A), both sides of the blank 3 heated by a high-frequency induction heating device are pressed and held using disk-shaped retainers 2 and 2 degrees fixed to the rotating shafts 1 and 1', respectively. ,
Next, with one rotating shaft 1' fixed, the other rotating shaft l
When the blank 3 is rotated in the direction of the arrow in the figure by an amount corresponding to the helix angle of the helical gear used to manufacture the blank 3, it becomes as shown in Figure 1 (B).
As shown in FIG. 2, the helical gear 4 is twisted and plastically deformed between its both end surfaces, and has straight teeth on the outer circumferential surface or helical teeth with approximately a predetermined helix angle.

In this case, each rotating shaft 1. lo may be rotated in opposite directions by an amount corresponding to half the helix angle of the helical gear.

Next, the shaft 6 of the guide mold 5, which has a tooth profile with a precise helix angle formed on its outer periphery, is moved in the direction of the arrow shown in FIG. In this state, when the rotating shaft 1.1' is rotated in the same direction while holding the helical gear 4, the guide mold 5 is moved to the helical gear 4.
The helical gear meshes with the helical gear 4 and rotates freely in the direction shown by the broken line in the figure, thereby correcting the error in the tooth trace direction of the helical gear 4 and producing a helical gear having a predetermined helix angle.

In this way, the easy-to-manufacture spur gear is used as a flank, and this blank is made into a helical tooth shape by controlling the helical angle between its both end faces, and the guide mold 5 is used to correct any errors in the tooth helical direction. An accurate angle can be obtained, and the degree of freedom of a given torsion angle can be obtained.

〔Effect of the invention〕

The present invention has the effect that a helical gear with an accurate helix angle can be obtained, and the degree of freedom in determining a predetermined helix angle is large, so that a helical gear with an arbitrary helix angle can be manufactured at a low cost.

[Brief explanation of the drawing]

Figures 1 (^), (B), and (C) are explanatory diagrams showing the manufacturing process of the embodiment of the present invention, Figure 2 is a perspective view of the helical gear to be manufactured, and Figures 3 to 5 are explanatory views showing the manufacturing process of the embodiment of the present invention. Fig. S3 is an explanatory diagram of a rolling method, Fig. 4 is an explanatory diagram of an extrusion forging method, and Fig. 5 is an explanatory diagram of another extrusion forging method. 1 Two rotating shafts 2: Holding mold 3: Flange 4: Helical gear 5 Guide mold 6: Shaft

Claims (1)

[Claims] Both side end faces of a blank previously manufactured in the shape of a spur gear with a tooth profile similar to that of the helical gear to be manufactured are pressed and held to impart a circumferential twist between both end faces of the blank, and then the teeth of the blank and a predetermined A method for manufacturing a helical gear, which comprises correcting a helical tooth profile formed by twisting on the blank by meshing and rotating a die in which a helical tooth profile has been formed.