JPS63309349A - Forging method for hollow article and its device - Google Patents

Abstract

PURPOSE:To spread the inner diameter of a blank, to contract the outer diameter and to thin the thickness of a product by roughening the blank inner diameter prior to drawing the outer diameter and finishing the inner and outer diameters thereafter. CONSTITUTION:An annular blank 8 is pushed into the annular space formed by a punch 3 and die hole 2 with the rolling reduction of a push-in means 7, the inner face is spread with the inner face of the blank 8 abutting to the tapered part 16 of the forming part 11 of the punch 3 and pushed into a recessed part 18. The blank 8 is then subjected to rolling reduction further, the outer peripheral face of the blank 8 is abutted to the tapered part 17 of a die 1 and according to the outer diameter being drawn the inner face of the blank 8 is filled up inside the recessed part 18 as well and the fill-up to the recessed part 18 is completed at the straight part of both forming parts 11, 14. And at the position of escape parts 12, 15 the inner and outer peripheral faces of the blank 8 are not brought into contact with either the punch 3 nor die 1 and the blank is formed in the product 19 of specified shape at this position.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method and apparatus for forging hollow products such as high carbon chrome bearing steel.

(Prior Art) Various methods have been proposed for forging ring-shaped products such as high carbon chrome bearing steel.

For example, as shown in FIG.
The following method is known for obtaining the ring-shaped product 19 with 0 by cold forging.

(2) A method in which a cylindrical blank is processed into a cup-shaped product 21 as shown in FIG. 4 using an extrusion punch, and then cut into the part shown by the broken line in the same figure to obtain a product 19.

■ As shown in Fig. 5, a mandrel 2 attached to the upper mold is placed on the inner surface of a ring-shaped material 23, which has an inner diameter slightly larger than the maximum diameter of the mandrel 22, which has a cross section that is opposite to the inner surface of the product.
2, insert the ring-shaped material 23 and mandrel 22 together into the die 24, and insert the mandrel 2 into the die 24.
Ring punch 25 and mandrel 22 that fit around the outer circumference of 2
and press down at the same time, so that the inner surface of the material 23 is aligned with the mandrel 22.
The processed product 26 is then extruded along the ejector 2.
7, and the product 19 is obtained by cutting along the broken line as shown in FIG.

(Problems to be Solved by the Invention) In the processing method (2) above, due to the high deformation resistance of high-carbon chrome bearing steel, large stress is applied to the extrusion punch.
Extrusion punches tend to bend to some extent. Therefore, even if it is attempted to process a long ring-shaped product, the length of the punch becomes long, which worsens uneven thickness of the product, and furthermore, the punch causes buckling, making it difficult to process. In addition, even in machining with a relatively small reduction in area, the extrusion punch is subjected to a stress that approaches the strength of the punch.
Even if you try to process a thin product with a large reduction in area, the applied stress will exceed the strength of the punch.
There was a problem in that the punch buckled and broke, making it impossible to process.

In addition, in method (2) above, the inner diameter of the ring material must be larger than the maximum diameter of the mandrel.
The outside diameter of the material must be strongly squeezed at the tapered part inside the die, which causes severe wear on the die and shortens its life. Further, as the mandrel descends, the positions of the die and the mandrel move relative to each other, so the molded portion of the mandrel is straight in the axial direction and has no relief.

Therefore, since the inner surface of the material is entirely in contact with the mandrel, seizure is likely to occur, and the life of the mandrel is unstable and short.

As mentioned above, there is no room for change in the inner diameter of the ring material or the relative positional relationship between the molded parts of the die and mandrel, and measures can be taken to reduce the load on the die and mandrel or change the above conditions to improve product quality. do not have.

The die and mandrel are aligned using a ring punch, and since the ring punch repeatedly goes in and out of the die during forging, the accuracy is not good in terms of tolerance and installation accuracy, and the ring product may be uneven. There were problems such as the meat being bad.

(Means for Solving the Problems) In order to solve the above problems, the present invention takes the following measures.

That is, the feature of the invention of the method for forging a hollow product is that a ring-shaped material is forced into a ring-shaped space formed by a punch and a die, and then passed through a forming part of the punch and a forming part of the die. , a forging method for forming a ring-shaped material into a predetermined shape, wherein before the outer diameter of the ring-shaped material is squeezed by the forming part of the die, the inner circumferential surface of the ring-shaped material is The purpose is to obtain a ring-shaped product in a predetermined shape by performing rough processing, then reducing the outer diameter of the ring-shaped material using a die forming section, and finishing forming the inner peripheral surface of the ring-shaped material using a punch forming section. .

In addition, the feature of the invention of the forging device for hollow products is that the ring-shaped material is forced into the ring-shaped space formed by the punch and the die, and then passed through the forming part of the punch and the forming part of the die. , a hollow product forging device for forming a ring-shaped material into a predetermined shape, the punch and the die are fixed so that they cannot move relative to each other, and the punch has a diameter smaller than the inner diameter of the ring-shaped material from the material pushing side. The die is formed with a guide part, a molding part having a diameter larger than the inner diameter of the material following the guide part, and a relief part having a smaller diameter than the molding part following the molding part, and the die has
From the material pushing side, there is a guide part with a diameter larger than the outer diameter of the ring-shaped material, a molding part with a smaller diameter than the material outer diameter, a molding part with a diameter smaller than the material outer diameter, and a relief part with a larger diameter than the molding part, respectively. The end of the forming portion of the punch on the material pushing side is offset from the forming end of the die toward the material pushing side.

(Function) According to the present invention, a ring-shaped material is pushed into a ring-shaped space formed by a punch and a die, and the ring-shaped material is shaped into a predetermined shape by passing through the forming part of the punch and the forming part of the die. When processing into products, the inner diameter of the material is rough-machined before the outer diameter of the material is narrowed, and then the inner and outer diameters of the material are finished, so the inner diameter of the material is expanded and the outer diameter is It is something that shrinks.

That is, according to the present invention, the inner diameter of the product is larger than the inner diameter of the material, and the outer diameter of the product is smaller than the outer diameter of the material, so that the wall thickness of the product can be reduced.

On the other hand, according to the conventional method (2), the inner diameter of the product is smaller than the inner diameter of the material, so the outer diameter must be reduced significantly and the wall thickness cannot be reduced.

That is, according to the present invention, a reduction in area of 55% or more can be achieved.

Further, according to the present invention, since there is a time difference between machining the inner and outer diameters of the material, the load stress acting on the punch and die is reduced.

(Example) Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, reference numeral 1 denotes a die, and a hole 2 is provided in the center of the die 1, penetrating in the vertical direction, and a punch 3 is inserted into the hole 2. The upper surface of the punch 3 and the upper surface of the die 1 are set as a road surface.

The lower part of the punch 3 is fixed to a holder 4, and the holder 4
is fixed to the die 1, and the punch 3 and the die 1 are immovable relative to each other.

A ring-shaped space is formed between the outer peripheral surface of the punch 3 and the inner peripheral surface of the hole 2 of the die 1, and this space is open upward.

An ejector 5 is fitted onto the lower part of the punch 3 so as to be movable in the vertical direction, and the ejector 5 is moved up and down in a ring-shaped space by a bushing rod 6 passing through the holder 4. In this raised position of the ejector 5, the upper end of the ejector 5 is in contact with the upper surface of the die 1 and the road surface.

Above the hole 2 of the die 1, a ring-shaped pushing means 7 that can be inserted into and removed from the ring-shaped space is provided so as to be movable in the vertical direction.

When the pushing means 7 is raised to form a space between the lower end of the pushing means 7 and the upper surface of the die 1, a ring-shaped material 8 is inserted into this space. , by lowering the pushing means 7, it is pushed into the ring-shaped space.

As shown in FIG. 2, the punch 3 has a guide portion 10 whose diameter is smaller than the inner diameter of the ring-shaped material 8 from the material pushing side.
and a molded part 1 having a diameter larger than the inner diameter of the material following the guide part 10.
1, and a relief part 12 having a smaller diameter than the molded part following the molded part 11.
is formed.

Further, the hole 2 of the die 1 also has a guide portion 13 having a diameter larger than the outer diameter of the ring-shaped material 8, and a guide portion 1 from the material pushing side.
3, a molded part 14 having a diameter smaller than the outer diameter of the material, and the molded part 1
A relief portion 15 is formed which has a larger diameter than the molded portion 14 following the molded portion 14 .

The material pushing side end of the forming part 11 of the punch 3 is formed into a tapered part 16, and the same end of the forming part 14 of the die l is also formed into a tapered part 17.

The tapered portion 16 of the punch 3 is located above the tapered portion 17 of the die 1.

Each molded part 11.14 following each said tapered part 16.17
is formed straight in the axial direction, and each molded part 11.14
The lower ends of the two face each other at the same position in the axial direction.

The molded part 11 of the punch 3 has a recess 1 along the axial direction.
8 is provided, and the bottom diameter of the recess 18 is larger than the outer diameter of the guide part 10.

The inner diameter of the ring-shaped material 8 is set to be a diameter between the maximum diameter of the molded part 11 of the punch 3 and the bottom diameter of the recessed part 18.

The ring-shaped material 8 is pushed into the ring-shaped space formed by the punch 3 and the die hole 2 under pressure by the pushing means 7, and first, the inner surface of the material 8 is pressed into the tapered part 16 of the forming part 11 of the punch 3. The inner surface is expanded and pushed into the recess 18. However, in this state, the inner surface of the material 8 does not fill the recess 18 and
There is a gap between the bottom 8 and the inner surface of the material 8 (as shown by the dashed line in FIG. 2).

Next, the material 8 is further rolled down, the outer peripheral surface of the material 8 comes into contact with the tapered part 17 of the die 1, and as the outer diameter is narrowed down, the inner surface of the material 8 also fills the recess 18, and the image is drawn. The filling of the recess 18 is completed in the straight part of the forming part 11.14, and the inner and outer peripheral surfaces of the material 8 do not come into contact with either the punch 3 or the die 1 at the position of the relief part 12.15. First, at this position, the material is formed into a product 19 having a predetermined shape.

When the pushing process is completed, the pushing means 7 rises and the ejector 5 rises, pushing the product 19 into the die 1.
Push it upward through hole 2.

Thereafter, by cutting and removing the unprocessed end portion of the product 19, a desired product can be obtained.

Note that the present invention is not limited to the above embodiments.

(Effects of the Invention) According to the present invention: - Since the load stress applied to the punch is small, it has become possible to manufacture long or thin ring-shaped products.・Since the inner diameter of the material is smaller than the maximum diameter of the inner forming punch, and some inner forming is performed before the outer diameter of the material is squeezed by the die, subsequent squeezing with the die is only light and the life of the die is extended.・Since the punch is installed inside the die, no tensile stress is applied during processing, and since there is a relief at the bottom of the molded part, seizure is less likely to occur and the life of the punch is extended.

・Since the punch is fixed within the die, installation accuracy is improved, and the fitting tolerance between the punch and the die is also small, which improves uneven thickness of the product.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a forging device showing an embodiment of the present invention;
The figure is an enlarged view of the same main part, Figure 3 is a front view and sectional view of the hollow product, Figure 4 is a side view and sectional view showing the conventional example, Figure 5 is a sectional view showing the conventional example, and Figure 6 is It is a side view and a cross-sectional view of a product according to a conventional example. DESCRIPTION OF SYMBOLS 1...Die, 3...Punch, 8...Ring-shaped material, 11...Molding part of punch, 14...Molding part of die. 19...Hollow product. Patent Applicant: Kobe Steel, Ltd., Figure 7, Figure 2rA, Figure 3. Prisoner 4 Figure 5

Claims (9)

[Claims] (1) A forging method in which the ring-shaped material is forced into a ring-shaped space formed by a punch and a die, and then passed through the forming part of the punch and the forming part of the die, thereby forming the ring-shaped material into a predetermined shape. Before the outer diameter of the ring-shaped material is reduced by the forming part of the die, the inner peripheral surface of the ring-shaped material is rough-processed by the end of the forming part of the punch, and then the ring-shaped material is reduced by the forming part of the die. A method for forging a hollow product, characterized in that a ring-shaped product having a predetermined shape is obtained by reducing the outer diameter of the ring-shaped material and finishing forming the inner peripheral surface of the ring-shaped material using a punch forming section. (2) The method for forging a hollow product according to claim 1, wherein the ring-shaped material is processed by cold forging. (3) The rough machining of the inner circumferential surface of the ring-shaped material is performed through a tapered part whose diameter gradually increases, which is formed at the end of the punch forming part.
Forging method for hollow products described in Section. (4) The outer diameter of the ring-shaped material is drawn through a tapered portion formed at the end of the die molding portion, the diameter of which gradually decreases. Forging method for hollow products. (5) A recess along the axial direction is formed on the outer peripheral surface of the molding part of the punch, and when rough machining the inner peripheral surface of the ring-shaped material, the inner peripheral surface is processed to the extent that it does not contact the bottom of the recess. A method for forging a hollow article according to claim 1. (6) In the finishing molding of the inner circumferential surface of the ring-shaped material, the inner circumferential surface of the ring-shaped material contacts the entire circumference of the recessed portion of the punch-forming part. How to forge the product. (7) A hollow product that is formed into a predetermined shape by pushing the ring-shaped material into the ring-shaped space formed by the punch and die and passing it through the forming part of the punch and the forming part of the die. In the forging device, the punch and the die are fixed so as not to be relatively movable, and the punch includes a guide portion having a smaller diameter than the inner diameter of the ring-shaped material from the material pushing side, and a guide portion having a diameter smaller than the inner diameter of the material continuing from the guide portion. A large molding part and a relief part smaller in diameter than the molding part following the molding part are formed, respectively, and the die has a guide part having a diameter larger than the outer diameter of the ring-shaped material from the material pushing side, and a guide part continuing from the guide part. A forming part with a smaller diameter than the outer diameter of the material and a relief part having a larger diameter than the forming part following the forming part are formed, respectively, and the material pushing side end of the forming part of the punch is closer to the material pushing side than the same forming end of the die. A forging device for hollow products, which is characterized by being deviated. (8) The hollow product forging device according to claim 7, wherein a recess along the axial direction is formed on the outer peripheral surface of the forming portion of the punch. (9) The forging device for hollow products according to claim 7, wherein the terminal ends of the forming portions of the punch and die are located at the same position in the axial direction.