JPS5930499B2 - Precision die forging method for ring-shaped products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precision die forging method for ring-shaped products such as gears having a shaft hole in the center.

In normal closed-die forging, in which a hole is sealed by a die and a punch that fits into the die, material is sequentially filled into the die hole as it is rolled down. Force increases rapidly, filling is delayed, and ultimately, extremely large machining forces are required to complete filling.

In general, this processing force must be high enough to significantly damage or break the die, which hinders the implementation of precision die forging.

The same applies to die forging of ring-shaped products.

The present invention utilizes the presence of a through hole in the center of a ring-shaped product to perform die forging with a load as low as the die can withstand, with particular emphasis on precision forming of the outer periphery of the ring-shaped product. The present invention provides a precision die forging method for a ring-shaped product in which a series of processes including punching and forming the through-hole part are simultaneously completed using the same die.

Hereinafter, application to a spur gear will be explained in detail with reference to the drawings.

FIG. 1 shows the shape of the desired product, which is a spur gear 1 having teeth 2 on the outer periphery and a shaft hole 3 in the center.

In Fig. 2, closed die forging is performed using a punch 4 having the same shape as the product spur gear 1 and a closed die 5 that receives the punch. A hole punch 6 having the same outer diameter is slidably fitted therein, and a hole 7 in the die 5 corresponding to the hole punch 6 is provided at the bottom of the die 5 .

An ejector 8 is slidably fitted into the punching die hole 7.

The punch 4, die 5, hole punch 6, and ejector 8 are each raised and lowered to the relative position by a hydraulic device (not shown).

As the material 9, a disk material having a diameter slightly smaller than the diameter of the root circle of the product spur gear 1 is used.

Die forging is performed using the tools and materials described above.

This processing is as follows. The explanation will be given assuming that the dice 5 are fixed.

First, the material 9 is inserted into the die 5.

At this time, the ejector 8 is fixed so that its tip is aligned with the bottom surface of the die 5 (see FIG. 2C).

Next, press down the hole punch 6 and press it into the center of the material 9 (
La hole? Open it.

The outer periphery of the material 9 is pushed upward and outward, and flows a little into the teeth of the die 5 (see Figure 2C).Then, the pressure of the ejector 8 is lowered and the hole punch 6 is pressed.
Further lower the hole and remove the bottom of the hole (thin walled part in the center) 10.

While the hole punch 6 is held in this state, the punch 4 is pressed down and closed die forging is performed here.

As a result, the material 9 flows outward and fills the teeth of the die 5 in a considerable amount (see FIG. 2C).

However, complete filling is not achieved, and the processing force increases rapidly during the process, slowing down the flow of the material.

When this machining force increases rapidly, the punch 6 is pulled up, and the punch is stopped before it comes out of the hole in the material to release the pressing force.

The material 9 is now allowed to flow inward, crushing the hole and pushing back the hole punch 6 somewhat upwards while the punch 4 resumes its descent (see second diagram).

At the same time, another part of the material 9 that has been rolled down also flows outward, and the filling of the teeth of the die 5 proceeds again.

Then, the filling of the material 9 into the die 5 is completed without much increase in machining force (see Fig. 2C).After that, the ejector 8 is released, and the hole punch 6 is pressed down again.
An annular inner protrusion 11 is punched out in the center of the material 9 between the punching die 7 and the shaft hole 3 (see FIG. 2C), and the machining is completed.

A high hydrostatic pressure is applied to the material 9 by the reduction blade of the punch 4, and the punching is similar to precision shearing, and the accuracy of the shaft hole 3 is high.

The method shown in FIG. 2C is effective when the buckling resistance of the material 9 of the blind hole bottom 10 is relatively large (and it is difficult to sufficiently reduce the machining force).

In addition, this precision die forging method is an improvement on the applicant's previous application (Patent Application No. 66401 of 1982).
At the stage of making the ring-shaped material 9, prior to drilling, the hole punch 6 was pushed in to form a thin blind hole bottom 10 in the center, and this hole bottom 10 was punched out. The aim is to reduce the thickness and amount of scraps and improve material yield.

Refer to FIG. 3C, which shows a modification of the present invention.

The method shown in this modification is fundamentally different from the precision die forging method shown in FIG. 2 in the steps C to D in FIG. 3, compared to the method shown in FIG. 2C.

Other than that, the method is almost the same as that shown in FIG. 2, so detailed explanation will be omitted.

That is, as shown in FIG. 3B, the hole punch 4 is pressed down (lowered) to make a blind hole in the center of the material 9.

At this time, the outer circumferential portion of the material 9 is pushed upward and outward, and slightly flows into the teeth of the die 5.

While holding the hole punch 6 in the state shown in FIG. 3B,
The punch 4 is pressed down to perform closed die forging.

At this time, the material 9 flows outward and fills the teeth of the die 5 in a considerable amount (see FIG. 3C).

However, even in this case, complete filling is not achieved, the processing force increases rapidly during the process, and the flow of the material becomes slow.

When this machining force increases rapidly, the punch 6 is pulled up, and the punch is stopped before it comes out of the hole in the material to release the pressurizing force.

Material 9 is now allowed to flow inward, crushing the hole and
The punch 4 resumes its descent while pushing the hole punch 6 back upwards.

At the same time, a part of the material 9 that has been rolled down also flows outward, and the filling of the teeth of the die 5 proceeds again.

At this time, a depression 13 is formed on the bottom surface of the blind hole due to buckling (see the third diagram).

Then, as shown in FIG. 3E, the filling of the material 9 into the die 5 is completed without a significant increase in processing force.

After that, the ejector 8 is released, the hole punch 6 is pressed down again, and the shaft hole 3 is punched in the center of the material 9 between it and the hole die 7 (the same as the precision die forging method shown in FIG. 2). (Refer to Figure 2C), the machining is completed.

As described above, in the precision die forging method for link-shaped products of the present invention, a hole punch and a hole die are provided for the punch and die for closed die forging, respectively, and an ejector is inserted into the hole die, and the ejector is not used except when necessary. First, a hole punch is inserted into the material to create a concave shape, and then the bottom of the concave is removed.The punch and die are used to perform closed die forging without relaxing the force, which increases the machining force rapidly. When the outward flow of the material becomes slow, the hole punch is pulled up to release the force and allow the material to flow inward, while at the same time promoting the outward flow and dicing the material. The filling of the mold is completed, and at the final stage, a through hole is punched out using a hole punch and a hole die to form a ring-shaped product all at once, without applying a force so strong that the tool breaks. This type of closed die forging, which was previously impossible to form sufficiently, can now be completely filled with material using practical processing power, making it possible to perform precise die forging.

At the same time, the through-hole in the center can be processed using the same tool, making it possible to mass-produce ring-shaped products.

In the second stage of forging process after the pressure force of the hole punch is released, buckling (indentation occurs) in the material under the hole punch,
The volume of cutting waste in the final drilling process is small, improving the yield rate of materials for products.

It is used in the mass production of ring products such as spur gears that have complex shapes on the outer periphery, and has a distinctive feature that improves accuracy and reduces costs.

Note that even if a hole punch is provided on the die side and a hole die and ejector are provided on the punch side, the same process can be performed without changing the gist of the method of the present invention.

Further, the principle of the present invention can be applied to the processing of helical gears by making the tooth profile provided on the die and punch into helical teeth to enable sliding movement accompanied by rotation of the punch or die.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional side view of a spur gear showing a typical example of a ring-shaped product obtained by the method of the present invention, and Figs. FIGS. 3A to 3F are diagrams showing tool operations in each process in a modification of the present invention. 1... Spur gear, 2... Teeth, total...
...Shaft hole, 4...Punch, 5...Dice, 6...Drilling punch, 7...Drilling die, 8... Ejector, 9...
Material, 10... Large dust ((zu), 11...
・Annular projection ((zu), 13...indentation.

Claims (1)

[Claims] 1 A part of the closed die forging die and a punch are each configured with a slidable drilling punch and an opposing drilling die hole, and an ejector is slidably fitted into the drilling die hole. Insert a material with a diameter of λ slightly smaller than the inner diameter into the die, first fix the ejector, press the hole punch into the material to make a hole, and while holding this state, insert the punch into the die. The material is press-fitted into the die for closed die forging, and when the outward flow of the material filling the die becomes slow due to the sudden increase in pressure during the pressurization process, the hole punch is pulled up. , the pressurizing force is released before the material is pulled out of the hole, and the hole punch is pushed back somewhat while crushing the hole in the material, allowing the material to flow inward while at the same time causing the material to flow outward. The precision of a ring-shaped product is characterized in that the ejector is released, the punch is extruded again, and the hole is punched into the material between the hole punch and the hole die. Die forging method.