JP3252924B2 - Hot forging method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot forging method for hot forging a cut piece obtained by cutting a long bar.

[0002]

2. Description of the Related Art In the above-described hot forging method, a heating step of heating a long bar to a hot state, and a step of heating the bar in a state where the heated bar is continuously arranged in series are performed. Continuously cut from the end in the direction perpendicular to the axis to continuously obtain cut pieces, and hot forging process for continuously hot forging each cut piece with a forging die and continuously obtaining forged products are doing.

[0003]

In the above-described method, as described above, in the cutting step, heated rods are continuously arranged in series. for that reason,
The shaft ends of two adjacent bars are bonded by heat, and FIG.
As shown in (A), a cut piece 100 having a seam 101 may occur. The detection device identifies the binding between the front and rear bar ends, and thus the cut piece 10 having the seam 101 is used.
The forged product 200 shown in FIG. 6B obtained by forging 0 has a defective portion 201 that causes a decrease in strength, and is regarded as a defective product.
However, the defective portion 201 is difficult to identify from the external appearance, and may be mixed into a non-defective product.

The present invention has been made in view of the above circumstances, and has as its object to detect a forged product having a defect formed at a seam and to provide a hot forging which is advantageous for ensuring the strength of the forged product. There is a way to provide.

[0005]

According to the hot forging method of the present invention, a long bar having a cutout at at least one shaft end is used, and the bar is heated to a hot state in a heating furnace. A heating step of continuously cutting the bar in a direction perpendicular to the axis from its end in a state where the heated bar is continuously arranged in series, and a cutting step of continuously obtaining cut pieces; Hot forging a piece with a forging die and continuously performing a hot forging process of continuously obtaining a forged product and a weight measuring process of measuring the weight of the forged product and judging the quality of the forged product based on the weight. It is characterized by the following.

It is preferable that the bar has a notch at both shaft ends. The reason for this is that the presence of these large deficient portions results in large weight fluctuations, and makes it easy to determine the quality of the forged product. The missing portion means a portion where the material meat is missing. The notched portion includes, for example, a portion that is cut off by removing burrs for removing cutting burrs and the like, a portion that is cut into a special shape, and the like.

[0007]

[Function] Since a cut portion is formed at the shaft end of a bar, a forged product obtained by forging a cut piece having a joint between shaft ends has a large degree of weight shortage. Therefore, if the weight of the forged product is measured, the quality of the forged product is determined based on the weight.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method of the present invention will be described with reference to FIGS. In this method, a long bar 1 (material: structural steel or alloy steel, cross section: circular) shown in FIG. 1A is used, and both shafts of the bar 1 are used. The notch 10 is formed at the end 1a with a grinder, a cutting tool, or the like. The notch 10 is shown in FIG.
As shown in FIG. 1B, a chamfered shape having an inclined surface 10c may be used. Alternatively, as shown in FIG.
It is good also as step shape provided with e. Note that the missing amount H can be appropriately selected as needed.

As shown in FIG. 2, a plurality of induction heating type heating furnaces 2 arranged in series are used, and a number of bars 1 are placed on a conveyor and supplied in series from an inlet 2a of the heating furnace 2. And the rod 1 is continuously kept in a hot state at 100 to 1200 ° C.
The heating is performed to a certain degree, and the material is discharged from the outlet 2b of the heating furnace 2 on the other side. Next, as shown in FIG. 3, the heated bars 1 are conveyed in the direction of arrow X1 in a state of being continuously arranged in series by a pinch roller or the like. In this state, the shaft end 1 of the adjacent bar 1
a easily adhere to each other. This is because the bar 1 is heated to a red hot state.

Using a cutting device 3 having a fixed blade 30 and a movable blade 31, the bar 1 is cut from its end into a fixed length in the direction perpendicular to the axis, and a cut end face as shown in FIG. The cut pieces 4 with 40 are continuously obtained. In this embodiment, as shown in FIG. 3, a photoelectric tube device 5 is provided at a position before the cutting device 3. The photoelectric tube device 5 includes a light emitting unit 50 and a light receiving unit 52 that face each other via the bar 1 that is transported in series. Here, arrow X in a state of being continuously arranged in series
The light-emitting portion 5 of the photoelectric tube device 5 is attached to the bar 1 conveyed in one direction.
Light is emitted from 0 and received by the light receiving unit 52. Thereby, the joint P between the shaft ends 1a of the bar 1 is detected. in this case,
Since the distance L1 between the photoelectric tube device 5 and the cutting device 3 and the transport speed V1 of the bar 1 are set in advance, it is possible to know the time when the cut piece 4 having the seam P reaches the cutting device 3, and at this time, Then, the cut piece 4 having the seam P is removed.

After cutting as described above, FIG.
Using a closed forging device 7 provided with an upper die 70, a lower die 71 and an extrusion pin 72 shown in FIG.
To obtain a forged product 8. Here, the closed forging is also referred to as closed forging, and is a forging that does not substantially generate burrs, and therefore, the volume of the molding cavity substantially corresponds to the volume of the cut piece 4, and the volume of the cut piece 4 is a forged product. 8 corresponds to a volume of 8. After the forging, the forged product 8 is released by the operation of the extrusion pin 72. Thereafter, as shown in FIG. 4C, the central bottom portion 8a of the forged product 8 is removed using a punching die 75. Then, the forged product 8 has a ring shape.

FIG. 5A shows a cut piece 4 having a joint P between the shaft ends 1a of the bar 1. When the cut piece 4 having the seam P is hermetically sealed and forged, a defective portion P2 caused by the seam P is generated inside the forged product 8, as shown in FIGS. The underfill portion P3 is generated, and the forged product 8 is lighter than the allowable weight width of the non-defective product, that is, the weight is insufficient due to the influence of the underfill portion P3. The portions painted black in FIGS. 5B and 5C are the underfill portions P3. That is, in the closed forging, the lack of weight of the cut piece 4 appears as a missing portion P3 to which the material meat is not distributed.

When the hot forging process is completed as described above,
The forged product 8 is cooled to a measurable temperature. Then, the weight of the forged product 8 is measured using a weight measuring device, and if the weight is within the reference range, it is determined to be a good product. Judge as good.
In this embodiment, the defective product is 5 to 10% of the weight of the non-defective product.
It is designed to be lighter.

The weight measuring device used may be a system for measuring the absolute weight of the forged product 8, or a balance measuring system in which a reference weight is provided on one of the balances and the forged product 8 is placed on the other. A method may be used. The forged product 8 determined to be non-defective is subjected to a process such as gear cutting in a later step, and is used for manufacturing gears and the like. (Effects of Embodiment) As described above, in this embodiment, since the notch 10 is formed in the shaft end 1a of the long bar material 1, the cut piece having the joint P between the shaft ends 1a is provided. The forged product 8 obtained by forging 4 has a greater degree of weight shortage than a good product.
Therefore, if the weight of the forged product 8 is measured, the quality of the forged product 8 is determined based on the weight of the weight. Forged product 8
This is advantageous in terms of ensuring strength.

Further, as shown in FIG.
When the phototubes are transported in series, the seam P is detected by the photoelectric tube device 5. In this respect, in this embodiment, the long bar 1
Since the notch 10 is formed at the shaft end 1a, the amount of light received by the light receiving unit 52 greatly changes due to the influence of the notch 10. Therefore, it is easier for the photoelectric tube device 5 to detect the seam P between the shaft ends 1a of the bar 1, which is advantageous.

(Other Examples) In the above embodiment, the weight is measured after the hot forged product 8 is cooled, and when a long cooling time is required, liquid cooling, air cooling, or the like is used. A step can also be performed. In addition, the method of the present invention is not limited to the embodiment described above and shown in the drawings. For example, the notch 10 at the shaft end 1a of the bar 1 may be a hole, a groove, or a notch. In addition, the heating furnace 2 is not limited to the induction heating method, and can be carried out by appropriately changing it without departing from the scope of the invention.

[0017]

According to the method of the present invention, since the notch which actively promotes the lack of weight is formed at the shaft end of the long bar, the cut piece having the joint between the shaft ends can be cut. Forged products forged have a large degree of weight shortage. Therefore, if the weight of the forged product having such a seam is measured, the quality of the forged product can be easily determined based on the weight of the forged product. Therefore, it is advantageous in assuring the strength of the forged product.

[Brief description of the drawings]

FIG. 1A is a side view of the vicinity of a shaft end of a rod material,
(B) (C) is a side view of the vicinity of the shaft end of the bar having the notch.

FIG. 2 is a configuration diagram schematically showing a heating step.

FIG. 3 is a configuration diagram schematically showing a cutting step.

4A and 4B show a case where a non-defective product is manufactured; FIG. 4A is a side view of a cut piece which is a non-defective product, FIG. 4B is a cross-sectional view of a closed forged state, and FIG. It is sectional drawing of the forged product used as a non-defective product.

5A and 5B show a case where a defective product is manufactured. FIG. 5A is a side view of a cut piece having a seam that becomes a defective product, and FIG. Yes,
(C) is a cross-sectional view of a state where a forged product having a seam, which is a defective product, is deburred.

FIG. 6A is a side view of a cut piece having a seam according to the related art, and FIG. 6B is a cross-sectional view of a defective forged product having a seam according to the related art.

[Explanation of symbols]

In the figure, 1 is a bar, 1a is a shaft end, 10 is a cutout portion, P is a seam, 2 is a heating furnace, 3 is a cutting device, 4 is a cut piece, 7 is a closed forging device, and 8 is a forged product. .

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-75740 (JP, A) JP-A-63-93441 (JP, A) JP-A-49-134562 (JP, A) 92414 (JP, U) JP-B 35-13205 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21J 1/00-13/14 B21J 17/00-19/04 B21K 1/00-31/00

Claims (1)

(57) [Claims] 1. A heating step of using a long bar having a cutout at at least one shaft end and heating the bar to a hot state in a heating furnace; and heating the heated bar. In a state of being continuously arranged in series, the bar is continuously cut from its end in the direction perpendicular to the axis, and a cutting step of continuously obtaining cut pieces, and hot forging each of the cut pieces with a forging die. A hot forging step of continuously obtaining a forged product, and a weight measuring step of measuring the weight of the forged product and determining the acceptability of the forged product based on the weight. Method.