JP4639089B2 - Method for manufacturing ring with inner peripheral projection made of hollow metal tube - Google Patents

Description

  The present invention relates to a method for manufacturing a ring with an inner peripheral projection by cold forging using a hollow metal tube as a raw material.

Regarding the manufacturing method of the ring with the inner peripheral projection, as a conventional technique, a manufacturing method by a hot forging method is shown in the following Patent Document 1, and FIG. 8 uses the hot forging method shown in this Patent Document 1. It is explanatory drawing of the manufacturing process of the ring with an inner periphery protrusion.

  In this manufacturing method shown in FIG. 8, first, a steel pipe is cut into a predetermined length in the first step to form a raw material, the raw material is heated to a predetermined temperature in the second step, and a lower mold is formed in the third step. And the forging machine with the upper mold attached, the forged material obtained in the second step is hot forged, and the ring part (cylindrical part) and the disk-like part are integrated (the longitudinal section is H-shaped) In the fourth step, in the fourth step, the center part of the disk-shaped portion whose longitudinal cross-sectional shape obtained in the third step is H-shaped is punched out with a punch to form a ring with an inner peripheral projection, and in the fifth step, This is a method of finishing the scale of the ring with the inner peripheral projection with a cutting tool.

  In addition, the same document shows a manufacturing method for performing CRF (cold ring rolling) after cold forging, and FIG. 9 is an explanatory diagram of a manufacturing process of a ring with inner peripheral projections for performing CRF after cold forging. is there

In this manufacturing method shown in FIG. 9, first, a steel pipe is cut into a predetermined length in the first step to form a raw material, and in the second step, the raw material is installed by a forging apparatus to which a lower die and an upper die are attached. The bulging ring with the inner and outer surfaces protruding into a convex shape, and then the bulging ring obtained in the second step in the third step is used as a molding roll for outer surface processing and for inner surface processing having concave grooves on its outer peripheral surface. This is a method of forming protrusions on the inner peripheral surface by pressing with a mandrel and pressing in the direction of the mandrel while rotating the forming roll.
Japanese Patent Laid-Open No. 2001-300668

  However, in the method by hot forging shown in FIG. 8 above, it is necessary to heat the raw material, and it is not possible to lack a cutting process for removing the generated scale. There are problems in that the yield decreases, the number of processes is large, and the efficiency is low.

  Further, in the method of performing CRF after the cold forging shown in FIG. 9 above, since the material is once set and the inner and outer surfaces are projected in a convex shape, the protrusion is formed on the inner peripheral surface by CRF. There is a problem that it is necessary to provide two types of equipment different in cold forging and CRF, the number of processes increases, and productivity decreases.

  The present invention has been made in view of the above problems, and provides a manufacturing method that has a simpler manufacturing process, higher yield, higher productivity, and lowers manufacturing costs compared to conventional hot forging methods. There is to do.

  Further, the present invention provides a manufacturing method in which the manufacturing equipment is simple, the equipment cost is low, the manufacturing process is simple, the yield is high, the productivity is high, and the manufacturing cost can be reduced compared with the method of performing CRF after cold forging. is there.

A first invention for achieving the above object is a cold forging method for a ring having an inner peripheral projection, which is made of a hollow metal tube, and has a cylindrical shape that constrains the outer peripheral shape of the material. after insertion into the outer diameter restraint die, provided with a surface forming a cylindrical section defining an inner surface shape of a ring, the inner peripheral surface of the inner peripheral protrusions Ri Sonawa the material side of the cylindrical portion, the cylindrical portion respectively closed a protrusion Ru smaller diameter der than the diameter, the first mold and the axis of the material by the second mold in which the corners of the cylindrical portion rounded in an arc shape and the protrusions of the connecting portion a cylindrical portion This is a cold forging method of a ring with an inner peripheral protrusion, characterized by forming the inner peripheral protrusion by forging in the direction and projecting the central part of the material radially inward.

A second invention is a cold forging method of a ring with an inner peripheral projection, wherein the hollow metal tube is a hollow metal tube obtained by processing a seamless steel tube in the first invention.

According to the first aspect of the present invention, there is provided a cold forging method for a ring having an inner peripheral projection, wherein a hollow metal pipe is used as a raw material, and a cylindrical outer diameter restraining metal that restrains the outer peripheral shape of the raw material. after insertion into the mold, and a cylindrical portion defining an inner surface shape of a ring, with a surface forming an inner peripheral surface of the inner peripheral protrusions Ri Sonawa the material side of the cylindrical portion, with a smaller diameter than the diameter of the cylindrical portion a protrusion Ru Ah, respectively have a, and forging in the axial direction of the material by the corners of the cylindrical portion rounded in an arc shape first mold and the second mold and the projecting portion of the connecting portion a cylindrical portion, material Since the central projection of the inner wall is projected radially inward to form the inner peripheral projection, the manufacturing equipment is simple, the equipment cost is low, the manufacturing process is simple, the yield is high, the productivity is high, and the manufacturing cost is reduced. The effect is that Moreover, since the protrusion has a diameter smaller than that of the cylindrical portion, there is an effect that the smoothness of the inner peripheral surface of the protrusion of the ring with the inner protrusion is improved.

Since the second invention is obtained by processing the seamless hollow steel pipe as a raw material, in addition to the effect of the first invention, a cylindrical body manufactured by hot forging from a round bar steel is used as the material. Compared with the case where it does, it is not necessary to punch and throw away the bottom part of forging, and since there is little cutting allowance, there exists an effect that a yield improves.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a ring with an inner circumferential projection made of a hollow metal tube according to an embodiment of the present invention, and FIG. 2 shows an inner circumferential projection made of a hollow metal tube according to an embodiment of the present invention. It is explanatory drawing of the cold forging apparatus of an attached ring, and has shown the state before forging. FIG. 7 is an explanatory view of the manufacturing process of the ring with the inner peripheral projection according to the embodiment of the present invention.

In FIG. 2, the upper mold 20 and the lower mold 30 have the same shape, and the upper and lower molds have large-diameter portions 22 and 32 and cylindrical portions 23 and 33 having a smaller diameter than the large-diameter portion following the large-diameter portion. , And the protrusions 21 and 31 having a smaller diameter than the cylindrical part are integrally formed, and the ridge line part at the tip of the protruding part is provided with an angle R (R ₃ ) to protrude from the cylindrical part. An angle R (R ₂ ) is applied to the connecting portion of the portion.

The small-diameter protruding portions 21 and 31 and the corner R (R ₃ ) are provided to eliminate the folding of the inner peripheral portion of the material 10 when the upper mold 20 and the lower mold 30 are stroked.

  The cylindrical portions 23 and 33 define the inner peripheral surface 14 of the ring with an inner peripheral projection, which is a finished product, and the protrusions 21 and 31 are inner peripheral surfaces of the projection portion 12 of the ring with an inner peripheral projection, which is a finished product. 13 is defined.

  In the first step shown in FIG. 7, the cylindrical body obtained by cutting the seamless steel pipe into a predetermined length or the cylindrical body separated in the fourth step of FIG. 5 (or FIG. 6) described later is used as a material. 2. Next, in the second step of the figure, this material 2 is inserted into a cylindrical outer diameter restraining die 40 for restraining its outer peripheral shape, and then a forging device to which an upper die and a lower die are attached. Then, the upper die is moved downward and the lower die is moved upward by the same stroke to forge the material 2 in the axial direction.

  FIG. 3 shows a state after the forging of the cold forging apparatus shown in FIG. 2, that is, a state where the upper die and the lower die are full stroked.

  In FIG. 3, as the lower mold 30 is raised and the upper mold 20 is lowered, the inner peripheral portion of the material 2 is brought closer to the axial central portion, and the central portion projects radially inward, thereby causing the inner peripheral protrusion to protrude. A ring is formed.

  FIG. 4 is a longitudinal sectional view of the ring with inner peripheral projections after forging by the cold forging device shown in FIG. Waves or irregularities are generated on the inner peripheral surface 13 of the projection after forging, and the smoothness is impaired, but the degree is small (FIG. (A)).

  The top and bottom dies may be brought into contact with the top surface during a full stroke, or the forging device may be designed so that a predetermined gap is ensured. The inner peripheral surface 13 of the projecting portion of a ring with an inner peripheral projection has a concave shape, which causes a flaw such as folding (FIG. 4B).

  That is, by adjusting the height and outer diameter of the upper and lower protrusions 21 and 31 of the upper and lower molds, undulation or unevenness of the inner peripheral surface of the projection after forging can be suppressed, and smoothness can be obtained. It is possible to reduce the cutting allowance in the cutting process.

  In the above description, the cold forging device is a vertical double acting type, and the die is divided into an upper die and a lower die. However, the present invention is not limited to this, and a single acting type or a horizontal horizontal type is also used. Or other formats may be used.

  Hereinafter, examples will be described in more detail with reference to FIGS. 1 to 7 used in the description of the above embodiment.

Product (finished product) specifications
Outer diameter D ₀ : 79 mm
Inner diameter D ₁ : 65.9 mm Thickness T _A : 6.55 mm
Protrusion inner diameter D ₂ : 61.8 mm
Wall thickness _T B: 8.6mm
Length B: 40.2mm
Material dimensions
Outer diameter: 79mm
Inner diameter: 65.2 mm Wall thickness: 6.9 mm
Length: 37.6mm
Material: SUJ2 (HRB105 or less)
Upper and lower mold dimensions:
Large diameter part outer diameter 79mm x height 50mm
Cylindrical part outer diameter 65.9mm x height 16.7mm
Protruding part outer diameter 62.8mm x height 2.5mm
Angle R R ₁ : 1 mm R ₂ : 6 mm R ₃ : 1 mm
Outer diameter restraint mold
80mm inside diameter
The specifications were as follows.

  When using a lathe to cut a seamless steel pipe with an outer diameter of 79 mm, an inner diameter of 65.2 mm, a wall thickness of 6.9 mm, and a length of 6 m to a length of 37.6 mm with a parting tool, and using this as the material Was set as Example 1, and the heights of the projecting portions of the upper and lower molds were set to 3.0 and 2.0 mm, and the other dimensions were the same as those of Example 1, and were set as Examples 2 and 3, respectively. Moreover, the case where the cylindrical body manufactured by hot forging was used for the raw material in Examples 1, 2, and 3 was set to Examples 4, 5, and 6.

  FIG. 5 is an explanatory view of a material manufacturing process (stepless cylinder) by hot forging according to the embodiment of the present invention, and the materials according to Examples 4, 5, and 6 are obtained by hot forging shown in FIG. I use what I made.

  In FIG. 5, in the first step, a round steel bar having an outer diameter of 40 mm and a length of 6 m is cut into a length of 42.5 mm with a parting tool using a lathe, and this is used as a base material for hot forging. A steel bar material is manufactured, and in the second step, the round steel bar material is heated to 1050 ° C. and forged and preformed (outer diameter 78 mm, thickness 14.7 mm). In the third step, the cup-shaped body is forged, and finally in the fourth step, the bottom surface of the cup-shaped body is separated by shearing to form a cylindrical body (outer diameter 79 mm, inner diameter 62.5, Width (height) 37.6 mm).

  FIG. 6 is an explanatory view of a material manufacturing process (multistage cylinder) by hot forging according to the embodiment of the present invention. One of the multistage cylinders shown in FIG. 6 is hot forged shown in FIG. It can replace with the raw material which concerns on, and can be set as the raw material shown in the present Example 4,5,6.

  In FIG. 6, a round steel bar material (outer diameter: 40 mm, length: 49.5 mm), which is a base material for hot forging, is manufactured by cutting a long round steel bar in the first step as shown in FIG. In the second step, the round steel bar material is heated to 1050 ° C., forged and preformed (outer diameter 78 mm, thickness 20.2 mm). In the third step, a forged cup-shaped body is formed. Finally, in the fourth step, the step and bottom of the cup-shaped body are separated by shearing to produce two cylindrical bodies having different outer diameters. A process of obtaining a cylinder having a larger outer diameter (outer diameter 79 mm, inner diameter 62.5, width (height) 37.6 mm) is shown. Also in this case, a hollow metal tube material can be used as in the fourth, fifth, and sixth embodiments.

Then, in order to compare with the above-described embodiment, the protrusions of the upper and lower molds are removed, the corner R (R ₂ ) is applied to the tip ridge line portion, and the other shapes and dimensions are the same as those in Embodiments 1 and 4. These were designated as Comparative Examples 1 and 2.

  Table 1 shows the forging results according to the difference between the material 2 of the above specifications and the upper and lower molds.

As shown in Table 1, the dimensions of the finished products of Examples 1 to 6 are the outer diameter D _{0, the} inner diameter D ₁ (thickness T _A ), the protruding portion inner diameter D ₂ (thickness T _B ), and the length B In both cases, products satisfying the product specifications were obtained.

  Further, regarding the smoothness of the inner peripheral surface 13 of the protrusion, in Examples 1 and 4, the gap t between the top surfaces at the time of full stroke of the upper and lower dies is 1.8 mm, and minute waviness is generated (FIG. 4 (A )). In Examples 2 and 5 and Examples 3 and 6, the gaps t between the top surfaces of the upper and lower molds at the time of the full stroke are 0.8 and 2.8 mm, respectively, and the smoothness of the inner peripheral surface 13 of the protrusion is very small. It was good in both convex and concave shapes.

On the other hand, the dimensions of the finished products of Comparative Examples 1 and 2 satisfied the product specifications in all of the outer diameter D _0, inner diameter D ₁ (thickness T _A ), and length B, but the full stroke of the upper and lower molds large gap t between the top face and 6.8mm of time, the protrusion inner peripheral surface 13 is a large concave occur, inner diameter D ₂ was not measurable (Fig. 4 (B)).

It is a longitudinal cross-sectional view of the ring with an inner periphery protrusion which uses the hollow metal tube which concerns on embodiment of this invention as a raw material. It is explanatory drawing of the cold forging apparatus of the ring with an inner peripheral protrusion which uses the hollow metal pipe which concerns on embodiment of this invention as a raw material. It is a figure which shows the state after the forge of the cold forging apparatus shown in FIG. It is an expanded longitudinal cross-sectional view of the ring with an inner periphery protrusion after the forge of the cold forging apparatus shown in FIG. 2, (A) shows the case where there is a protrusion in the upper and lower molds, and (B) shows the case where there is no protrusion. . It is explanatory drawing of the manufacturing process (stepless cylinder) of the raw material by the hot forging which concerns on embodiment of this invention. It is explanatory drawing of the manufacturing process (multistage cylinder) of the raw material by hot forging which concerns on embodiment of this invention. It is explanatory drawing of the manufacturing process of the ring with an inner peripheral protrusion which concerns on embodiment of this invention. It is explanatory drawing of the manufacturing process of the ring with an inner peripheral protrusion using the hot forging method which concerns on a prior art example. It is explanatory drawing of the manufacturing process of the ring with an inner periphery protrusion which performed CRF after the cold forging which concerns on a prior art example.

Explanation of symbols

1 ... Cold forging device 2 ... Material (hollow metal tube)
10 ... Ring with inner peripheral projection 11 ... Cylindrical portion 12 ... Protrusion
13 ... Inner peripheral surface (projection part) 14 ... Inner peripheral surface (cylindrical part)
20 ... Upper mold (first mold)
21 ... Projection part 22 ... Large diameter part 23 ... Cylindrical part 30 ... Lower mold (second mold)
31 ... Projection part 32 ... Large diameter part 33 ... Cylindrical part 40 ... Outer diameter restraint die

Claims (2)

A cold forging method for a ring having an inner peripheral projection, comprising a hollow metal tube as a raw material, and after inserting the raw material into a cylindrical outer diameter restraining mold for restraining the outer peripheral shape of the raw material, cylindrical portion defining a ring of inner surface shape and provided with a surface forming an inner peripheral surface of the inner peripheral protrusions Ri Sonawa the material side of the circular column portion, Ru smaller diameter der than the diameter of the cylindrical portion projecting portions If, respectively have a, and forging the corners of the columnar portion by the first mold and the second mold has a connection portion of the protruding portion and the cylindrical portion rounded in an arc shape in the axial direction of the material, the A cold forging method for a ring with an inner peripheral protrusion, wherein the inner peripheral protrusion is formed by projecting a central portion of the material radially inward. 2. The cold forging method for a ring with inner peripheral projections according to claim 1 , wherein the hollow metal tube is a hollow metal tube obtained by processing a seamless steel tube.

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