JPH06179035A - Manufacture of crank shaft - Google Patents

Abstract

PURPOSE:To uniform a wall thickness of an arm part and to rationally and in-expensively manufacture by pressing in a pin equivalent part with a punch, supporting the punch and forging the arm part. CONSTITUTION:A 180 deg. bending is executed by pressing a pin equivalent part 2 of a crank shaft single blank 6 with a specific punch 7 preliminarily prepared and pressing in between two corresponding supporting rolls 8, 8 supported with a supporting stand 9. In this case, the thickness of the arm 3 is reduced with forging at the same time as 180 deg. bending, and made to the uniform thickness by making a clearance distance between the supporting rolls 8, 8 smaller than a sum value of a total thickness of left and fight both arms 3 of the crank shaft single blank and the thickness of the punch 7. Further, after once executing the 180 deg. bending, as the punch 7 is inserted between the arms 3, the thickness of the arm 3 is more made uniform by repeating the forging thickness reduction pressing in between the supporting rolls 8, 8 repeatedly if necessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semi-assembled crankshaft for a high power engine such as a ship by forging.

[0002]

2. Description of the Related Art Conventional methods for manufacturing a single crankshaft are roughly classified into three types: a ring forging method, a bending forging method, and a die forging method. Among these, in the method of forging a single crankshaft by bending, a steel ingot is forged to make a waste material 1 as shown in FIG. 1, and this waste material is bent by a bending machine 11 as shown in FIG. , The arm portions 3a and 3b are bent around the pin portion 2a, and the arm portion is elongated and rough-formed (forged) to be a crankshaft unit material, and the pin portion 2a is formed by using the molds 12a and 12b as shown in FIG. After the drawing process, the bent arms 3a and 3b from the center are shown in FIG.
As shown in Fig. 3, the plate is shaped by bending it 180 degrees with a large degree of work using a plate-like holding jig or the like,
Further, there are those manufactured by finish-molding a pin shape or a shaft shape with a drawing or a pressing die.

[0003]

In the conventional method as described above, when the crankshaft simple substance is bent by 180 ° as described above, the workability is large and the forming precision of the simple substance after rough forging is high. Machining defects are likely to occur due to non-uniformity, etc., and it is difficult to achieve roundness even if pin molding is finally carried out by fusing. Therefore, it is necessary to take a large allowance up to the final finish dimension, which is not economical because of a decrease in material yield and an increase in the number of post-machine finishing steps. An object of the present invention is to solve the above problems and provide a method for rationally manufacturing a crankshaft.

[0004]

That is, according to the present invention, in a manufacturing method for forging a single crank of a semi-assembled type crankshaft by bending, a crankshaft having two arm portions is formed by processing a forged blank material. As a single material, at the time of bending, set this material on two rotatable support rolls with the pin equivalent part centered, push the pin equivalent part with a punch, and forge the arm part with the punch and the support roll. And a wall thickness of the arm portion is equalized.

In order to manufacture a single material according to the present invention,
The forging process is mainly divided into the following two stages.

That is, in the first stage, a steel ingot is upset, and rough forging such as forging is performed to reduce or reduce cavities and segregation in the steel ingot. Then, as shown in FIG. 3b is flat and continuous, and an elongated waste material 1 having a pin-corresponding portion 2a at the center is formed. As shown in FIGS. 2A and 2B, the material 1 includes an upper die 4 having a die 4a that abuts on the upper surface of the pin-corresponding portion 2a, a central die 5a and a pin-corresponding portion that abut on the lower surface of the pin-corresponding portion 2a. 2a A crankshaft unit material having two arm portions 3 connected by a pin corresponding portion 2 by subjecting a rough material 1 to a two-sided forging with a lower die 5 composed of dies 5b and 5c for narrowing the side surface. Produce 6. In the future, the pin corresponding portion 2 will be the crankshaft pin portion 1 shown in FIG.
The part to be finally formed into 0, before the 180 ° bending process (FIG. 3) in the next step, until it reaches a substantially predetermined size, for example, the part formed by the upper die 4 and the central die 5a shown in FIG. 2 (b). Finish forging is preferably performed by a method such as die forging.

On the other hand, the arm portion 3 is formed to have a thickness including a forging allowance for forging during 180 ° bending (FIG. 3) in the step of forming the rough material 1, and at the same time, a predetermined width of the arm 3 is obtained by finishing. Finishing to the width dimension that can be done first
Finish the stage forging.

The present invention is characterized in that the crankshaft unit material 6 thus obtained is bent by the 180 ° bending apparatus shown in FIG. 3 to obtain the crankshaft product shown in FIG. That is, as the second stage forging process,
As shown in FIG. 3, the portion 2 corresponding to the pin of the crankshaft unit material 6
A special punch 7 prepared in advance (a perspective view is shown in FIG. 4)
180 ° bending is carried out by pressing the support rolls 8 and 8 between the two corresponding support rolls 8 supported on the support base 9 at this time. By making the total thickness of the left and right arms 3 of the shaft simplex material 4 and the total thickness of the punch 7 smaller,
Simultaneously with 180 ° bending, the thickness of the arm 3 is reduced by forging pressure to make it uniform. Further, after bending once by 180 °, the punch 7 is sandwiched between the arms 3 and the pressing force is again pushed between the support rolls 8 to reduce the thickness of the arms 3 repeatedly. Can be made more uniform. At this time, the thickness reduction rate can be adjusted appropriately.

By this series of forging operations, compared to the conventional crankshaft manufacturing by bending forging method, the dimension after the forging process is extremely accurate, and the finishing process by mechanical cutting in the subsequent process is significantly performed. Can be omitted.

[0010]

EXAMPLE A single Sulzer type RTA58 crankshaft was manufactured by the method of the present invention. The final shape is as shown in FIG. After forging a steel ingot consisting of the chemical composition (steel type KSF55) shown in Table 1, the top and bottom of the steel ingot are cut, and rough land forging (FIG. 1) is performed, and pin portion 2 including partial die forging is also performed.
And the peripheral forging was formed and forged (FIG. 2) to produce a rough forged single material 6. The thickness of the arm 3 at this point was 20 mm thicker than that of the final arm 3.

Next, with the crankshaft simple substance 6 being pressed against the pin portion 2 by the punch 7, two supporting rolls 8,
It was pushed in between 8 and bent by 180 ° (FIG. 3). At this time, the gap between the rolls 8 and 8 is such that the thickness of the arms 3 is 5 mm on each side, that is, the thickness of the arms 3 on the left and right sides is 1 mm, respectively.
It was adjusted so that the forging pressure could be reduced to 0 mm. After bending by 180 °, the gap between the rolls 8 was further narrowed by 20 mm and the same punch 7 was used for pushing. Table 2 shows the relationship among the pushing punch 7, the thickness of the arm 3 and the gap between the rolls 8 during this period.

[0012]

[Table 1]

[0013]

[Table 2]

After these hot forging operations, the front and back surfaces of the left and right arms 3 were extremely beautiful, and it was possible to obtain a machine that did not require cutting by a machine. Arm 3 after forging
The side surface of was finished by gas cutting and grinder processing.

[0015]

As described above, when the method for manufacturing a crankshaft according to the present invention is applied, when the weight of the required ingot according to the conventional method is 100, the present invention requires approximately 75% of the weight, and the machine The processing man-hours are half that of conventional products. Therefore, it can be said that it is an extremely economical method.

[Brief description of drawings]

FIG. 1 is a view in which a steel ingot is upset and expanded and then formed into a long and narrow waste material.

[FIG. 2] (a) is a two-sided forging of a rough material with an upper die and a lower die,
The figure which forms a crankshaft simple substance. (B) is a perspective view of a part of the upper die and the lower die (central die).

FIG. 3 is a diagram illustrating a situation in which a crankshaft single-piece material is forged between rolls, (a) is an explanatory diagram just before starting, and (b) is an explanatory diagram during forging.

FIG. 4 is a perspective view of a punch.

FIG. 5 is a front view of a product.

6 (a), (b) and (c) are explanatory views showing an outline of a conventional process.

[Explanation of symbols]

 1 Waste land material 2 Pin 2a Pin equivalent part 3 Arm part 4 Upper mold 5 Lower mold 6 Crankshaft single material 7 Punch 8 Roll 9 Support stand 10 Pin part 11 Processing machine 12 type

Claims (1)

[Claims] 1. A manufacturing method for forging a crank unit of a semi-assembled type crank shaft by bending, wherein a blank material formed by forging is processed into a crank shaft unit material having two arms, and when the bending process is performed, The material is set on two rotatable support rolls with the pin-corresponding part centered, the pin-corresponding part is pushed in by a punch, and the arm part is pressed by the punch and the support roll to reduce the wall thickness of the arm part. Crankshaft manufacturing method characterized by equalization.