JPH0620573B2 - Gear press forming die - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a molding die for forging a gear.

(Prior art and its problems) To form a conventional gear by cold forging, a wire rod is cut into a predetermined length to form a short cylindrical blank, and the blank is pressed to form a tooth of a completed gear. The gear is completed by preforming into a cylindrical body that corresponds approximately to the tip diameter and then performing a narrowing process with a hydraulic press.

In the above case, since the blank subjected to the surface treatment is narrowed down to the completed gear shape at once by one pressurization, the workability is high. Therefore, after the heat treatment, a step of performing a surface treatment on the blank and coating the phosphoric acid thick film is necessary in order to reduce friction with the mold.

Further, the load on the mold is large and the life of the mold is shortened.

In addition, the gear that is formed by drawing a blank by die casting is
It is a low-grade product with JIS accuracy of about 5th grade, and could not be incorporated into equipment that requires high accuracy.

Further, when the blank is die-cast, the blank must be pressed and held under static pressure for 5 to 6 seconds, resulting in poor manufacturing efficiency and a short die life, resulting in high cost.

The Applicant has attempted to form a blank into a gear shape stepwise by a transfer press, and has proposed to dramatically improve the productivity of gears.

At this time, if the gear-shaped blank before completion is driven into the gear-shaped die hole of the forging die while the core is misaligned or the phase is shifted, there is a problem that the die and the punch are damaged. .

The present invention reveals a forging die having a guide bevel that reliably guides a gear-like blank into a mold cavity.

(Means for Solving the Problem) The forging die of the present invention is a forging die for forming a gear from a blank through a plurality of forging steps, and each forging die (14) (15) (16) The guide slope (17) is formed on the opening edge of the mold cavity corresponding to the gear shape of
7) is a cone (1 with a maximum diameter slightly larger than the maximum diameter of the mold cavity).
7a) and chamfered portions (17b) (17b) that are chamfered diagonally on both sides of the tip of the ridge (14b) of each mold cavity.

(Operation and effect) A guide slope is formed on the opening edge of the die cavity of the forging die,
Since both ends of the ridge of the mold hole are inclined at an angle, when the gear-shaped blank is transferred to the next forging station and driven into the mold hole, the core or phase of the mold hole and the blank is Even if it is slightly deviated, it is possible to prevent the blank from smoothly entering the mold cavity by being guided by the guide slope and to prevent the blank from being caught between the opening edge of the die and the punch and destroying the die and the punch.

(Example) FIG. 1 shows a material cutting station S1, two preforming stations S2, S3 and three forging stations S.
4 shows a plan view of a forging part of a transfer press having 4, S5 and S6, and blanks B1 to B5 and finished gears (5) processed by each station. The protruding pins (2), (21), (22) and (23) and the punching punches (24) provided corresponding to each preforming and each forging station are shown as being shifted rearward from the standby fixed position. There is.

The transfer press die block (1) includes a cutting quill (11), a first preforming die (12), and a second preforming die (1).
3), a first forging die (14), a second forging die (15) and a third forging die (16) are provided.

A ram (4) is arranged so as to be capable of reciprocatingly facing the die block (1), and the ram (4) is provided on the ram so as to face each of the above-mentioned dies and a forging punch is provided.
(3) (31) (32) (33) (34) are attached.

The wire rod (6) fed to the forging side through the through hole (11a) of the cutting quill (11) is sheared by a cutting rod (not shown) that reciprocates orthogonally to the axis of the quill. , Is transferred to the first preforming station S2 by the cutting rod.

Each preforming station S is located on the die block (1).
There is provided a transfer device (not shown) for transferring the blanks B2, B3, B4, B5 formed at 2, S3 and the first and second forging stations S4, S5 to the next station.

The die holes (12a) (13a) of the first and second preforming dies (12) (13) have a circular cross section, and the bottom of the first preforming die (12) is inclined by 45 ° with respect to the axis. The die hole (13a) of the second preforming die (13) formed on the slope (12b) is formed in a round shape so that the outer diameter of the bottom portion gradually decreases.

Both preforming dies (12) and (13) project into the center of the bottom and pin insertion holes (1
2c) and (13c) are opened, and the protruding pins (2) and (21) are slidably fitted.

The second preforming die (1
In 3), it is a little big.

Further, the opening edges of both the preforming dies (12) and (13) are formed with tapered surfaces (12d) and (12e) serving as guide surfaces for the blank.

The first, second, and third forging dies (14), (15), (16) die holes (14a) (15)
a) and (16a) are ridges (14
b) is projected.

The die holes are slightly larger in order from the first forging die (14) to the third forging die, and the die holes (1
The sectional shape of 6a) corresponds to the outer peripheral shape of the finished gear (5).

The depth of the die holes (14a) (15a) of the first and second forging dies (14) (15) is larger than the thickness of the finished gear (5), and the bottom of the die holes is relative to the axis. Projecting pin insertion holes (14c) (15c) are opened in the center of the mold hole and projecting pins (22) (23) in the holes.
Is slidably provided.

The tip of the protruding pin (22) of the first forging die (14) on the protruding side is formed on a flat surface (22a) orthogonal to the axis, and the second forging die (1)
The projecting side tip of the projecting pin (23) of 5) is formed with a driving projection (23a) for driving into the blank B4.

The third forging die (16) also serves as a punching die, and the sleeve (25) is slidably fitted in the inner part of the die so that the punching punch (24) is attached to the sleeve at the axial center of the sleeve. It is slidably provided with respect to it.

Blank B is placed on the ram side opening edge of each forging die (14) (15) (16).
Guide slopes (17) to securely guide 3, B4 and B5 into the mold cavity
Are formed.

As shown in Fig. 2, the guide slope (17) has a conical portion (17a) whose maximum diameter is slightly larger than the maximum diameter of the mold cavity, and a ridge of each mold cavity.
Chamfer (17b) (1
7b), and the line of intersection between the conical part (17a) and the chamfer (17b) is rounded so that it is not angular (in Fig. 2, the conical part and the chamfer are shown to make the guide surface easy to understand). Squared the intersection line).

As shown in FIG. 3B, the angle of the conical portion (17a) is optimally 60 °, and as shown in FIG. 3B, if the angle is 60 ° or more, the bottom of the blank and the mold cavity are Friction becomes too large, causing seizure. If it is smaller than 60 ° as shown in FIG. 3C, the distance L between the end face of the die and the inner end of the tooth bottom becomes long, and it becomes difficult to align the die and the punch. Also, due to the lengthening of the forging stroke, sagging occurs at the tooth tip,
Burrs are easily generated on the tooth bottom.

First, corresponding to the first and second preforming dies (12) (13),
The second pre-pressing punches (3) and (31) both have conical surfaces (3a) and (31a) which are raised at an angle of about 3 ° with respect to a surface orthogonal to the axis.

The first, second, and third forging punches (32), (33), (34), which are arranged opposite to the first, second, and third forging dies (14), (15), (16), are holes in the dies. Tooth surfaces (32a) (33a) (34a) are formed on the outer periphery corresponding to the shape.

Further, protrusions (32b) (33b) for forming recesses (55) (56) on the end faces of the blanks B3 and B4 are formed at the center of the tips of the first and second forging punches (32) (33). ing.

The third press punch (34) is provided with a through hole (34b) for discharging punching dust when the blank B5 is punched.

However, the blank B2 transferred from the cutting station S1 to the first preforming station S2 has a die-side tip outer periphery of 45 ° corresponding to the bottom shape of the die (12) and the tip shape of the punch at the station S2. It is formed on the tapered surface (53), and the other end surface is gently recessed from the outer circumference to the center.

The blank B3 transferred from the first preliminary station S2 to the second preliminary molding station S3 has a die-side tip surface rounded.

The blank B4 transferred from the second preforming station S3 to the first forging station S4 is
4 is formed into a substantially gear shape corresponding to the mold cavity, and a recess (55) is formed on the punch-side end surface corresponding to the tip of the punch (32).

The minimum inner diameter of the die hole (14a) of the first forging station S4 is slightly larger than the diameter of the preformed blank B3, and the opening edge of the die hole has the guide slope (17) inclined inward. When the blank B3 is transferred to the first forging station S4, even if the cores of the blank B3 and the mold cavity (14a) are slightly misaligned, the blank B3 can be smoothly driven into the mold cavity (14a).

In the first pressing step, the material of the blank B4 does not completely flow into the groove of the die hole (14a), so that the tip of the tooth profile of the blank B4 is not a complete tooth die.

The blank B5 reversed from the first forging station S4 and transferred to the second forging station S5 is formed into a substantially gear shape corresponding to the die hole (15a) of the station S5, and is formed on the end face on the punch (33) side. Also, a recess (56) is formed corresponding to the tip shape of the punch (33).

Since the guide sloping surface (17) is formed at the opening edge of the mold hole (15a) of the second forging station S5, both sides of the tip of the ridge (14b) of the mold hole (15a) are inclined obliquely. When the gear-shaped blank B4 formed in the first forging station S4 is transferred to the second forging station S5 and driven into the die hole (15a), the core or phase of the die hole and the blank B4 is slightly deviated. Also, the blank B4 is smoothly guided into the mold cavity (14a) by being guided by the guide slope (17).

The die hole of the second forging station S5 is slightly larger than the die hole (14a) of the first forging station S4, and both end faces are recessed, so that the blank B5 produced by the second forging station S5 is correspondingly formed. The outer shape is larger than the blank B4 that has been forged in the first forging station S4. However, even in the second forging station, the blank meat does not flow into the groove of the mold cavity (15), and thus the blank B
The tooth tip of No. 5 does not have a perfect tooth profile.

From the second forging station S5 to the third forging station S
The blank B5 transferred to No. 6 is punched (2
Hole punching is performed by 4), at this time, the material meat of the blank is strongly extruded in the outer peripheral direction, filling every corner of the groove of the mold cavity (16a), forged into a shape corresponding to the completed gear, and the sleeve ( The finished gear (5) is ejected by being ejected to 25).

The punching punch (24) is fixedly held at a fixed position in the die hole (16a) and punched when the blank B5 is driven by the forging punch (34) into the die hole (16a). Alternatively, the blank B5 can be punched by punching the blank punch B after punching the blank 16 with the die punch 16a.

In the example, the tip diameter is 13.07 mm, the root diameter is 10.31 mm, and the thickness is 8.1 m.
Produced 14 gears with m, hole diameter 4.0 and number of teeth at a rate of 4500 / hour.

As described above, since the blank is forged in a stepwise manner so as to gradually approach the completed gear, the workability in each die hole is small, the load on the die is reduced, and the life of the die is extended.

Since the forging is performed by the transfer press, the production efficiency is dramatically improved as compared with the conventional case of the static pressure forging by the hydraulic press.

When the blank is gradually brought closer to the shape of the finished gear and the blank is punched in the final stage of the mold cavity, the meat of the blank is extruded in the radial direction and the material meat is placed in every corner of the mold cavity. A highly accurate gear can be formed by spreading it. In the embodiment, the quality of JIS class 3 can be satisfied, and it is 1 depending on the inspection item.
I was able to clear the class.

Incidentally, it is of course possible to carry out the forging step excluding the preforming step in three or more steps, and various modifications can be made within the scope of the claims.

[Brief description of drawings]

FIG. 1 is an explanatory view of the forging process, FIG. 2 is a perspective view of the opening of the die in the first to third forging processes, and FIG. 3 is a sectional view of the same. (12) (13) (14) (15) …… Die (3) (31) (32) (34) …… Punch

Claims (1)

[Claims] 1. A forging die for forming a gear from a blank through a plurality of forging steps, wherein each forging die (1
4) A guide slope (17) is formed on the opening edge of the mold hole corresponding to the gear shape of (15) (16), and the guide slope (17) is a cone whose maximum diameter is slightly larger than the maximum diameter of the mold hole. Part (17a) and the chamfered part (17
b) Gear press forming die consisting of (17b).