JPS6289544A - Method and device for partial die forging of crank throw - Google Patents

Abstract

PURPOSE:To prevent a wrinkle, a flaw and a thickness reduction of a bend part by a tensile stress, and to reduce an excess metal and a working man-hour by placing a forging preform on a man metallic die provided with a back chamber metallic die and an anvil, and performing a rolling reduction to a punch provided with a pin forming recessed part. CONSTITUTION:A main metallic die 31 provided with a back chamfer control metallic die 32, a side face control metallic die 33 and an anvil 34 is installed in a press. On its metallic die, a forging preform 39 is placed with its center projecting part down. A punch 35 having a pin shape forming recessed part which has been attached to an upper ram is made to descend and bought to a rolling reduction to the bottom dead center. According to this method, by a tensile stress in the preform 39, generation of a wrinkle and a flaw of a bend corner part by the punch 35, and a thickness reduction generated in a back chamfer part of the opposite side are prevented. Accordingly, an excess metal of a crank throw is decreased and the yield of a material is improved, and a man-hour of a machine work is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to forging and forming a crank throw using a forging press.

(Prior Art) There are two types of crankshafts for marine diesel engines: assembled type and integral type. The assembled type is formed by shrink-fitting or welding the crank throw to the journal. As shown in FIG. 11, the names of the parts of this assembled type crank throw are as follows: 1 is called a web, 2 is a pin, 3 is a back chamfer part, and 4 is a back chamfer side part.

The conventional assembly type crank throw was formed as shown in FIG. That is, an ingot 7 having a chrysanthemum-shaped cross section and a top (riser) 5 side diameter larger than the bottom 6 side diameter is manufactured, an appropriate amount of the top side 5 and bottom side 6 of the ingot 7 are cut off, and a forging press is used. A bloom 8 having a square cross section and a handle for working is manufactured. This bloom 8 has a gourd-shaped planar shape and a side surface having a convex portion 9 at the center in the longitudinal direction, and a recess 1G at the top of the convex portion 9.
Next, use a U-shaped mold 12 whose bottom inner surfaces are narrower than the distance between its upper inner surfaces, and a punch 13 with a flat bottom. wasteland 1
1 with the convex part 9 facing downward, and place it in the press with the center between the sides of the mold and the longitudinal center of the forged rough ground 11 aligned,
The punch 13 is pressurized and bent. Pressed and bent forged wasteland 11
is taken out from the mold 12, an intermediate plate 14 having the same thickness as the finished web spacing is inserted between the webs, both webs 1 are pressed down with an anvil 15 attached to the press, and then pins 2
The finished shape 16 is obtained by molding the periphery.

(Problems to be Solved by the Invention) When using the conventional press-bending die 12, the thirteenth
As shown in the figure, the A-A section undergoes significant bending deformation,
Since the neutral point of bending deformation is located midway between A and A, material gathers on the punch side 17 of the rough ground 11, and material is insufficient on the punch side 18 opposite to the punch 13.

In the conventional method, the material on the punch side 17 is transferred to another place and the material cannot be supplied to the side opposite to the punch 13, so in the case where the punch 13 is located, excess material is caught in the forged waste body. Wrinkles 19 occur, and shrinkage 20 occurs on the side opposite the punch 13, which in extreme cases can cause cracks.

In addition, in the conventional method, there is no regulating mold for forging the peripheral part of the pin 2 of the crank throw, so it takes time to forge the peripheral part of the pin 2 with an anvil.
As shown in FIG. 14, since the molding accuracy is poor, it is necessary to have a large amount of excess thickness 21, and a large amount of machining allowance is required. Furthermore, since the surface forged with an anvil is extremely uneven, positioning for machining cannot be done unambiguously, and positioning requires a lot of manpower and time.

This invention solves the above-mentioned problems with conventional forging dies, and creates an assembled type crank throw forging that has no wrinkles or material shrinkage, has a high yield, and allows easy positioning for machining. The purpose is to obtain goods.

(Means for Solving the Problems) In order to achieve this object, the present invention is characterized in that the pin portion and the web around the pin are molded while being restrained by a mold. This invention has the following mold configuration. In other words, a pair of back chamfer regulation molds corresponding to the shape of a part of the back chamfer of a crank throw are mounted facing each other on the inner surface of a U-shaped main mold, and the inner surfaces of both pack chamfer regulation molds are attached to the inner surface of a U-shaped main mold. Attach a side regulating mold with a facing surface that corresponds to the side surface of the back chamfer of the crank throw, and place an anvil with a shape that corresponds to the shape of the pin on the piston side of the crank throw in the center of the main mold and on the side of the main mold. They are installed parallel to each other so that a punch with a shape that corresponds to the shape of the pin on the journal side of the crank throw can be press-fitted parallel to the side of the mold. These molds may be integrated.

(Function) A back chamfer regulation mold, a side regulation mold, and a main mold with an anvil were installed in the press, a punch was attached to the upper ram of the press, and the upper ram was lowered to the bottom dead center. At times, the anvil and punch are installed facing each other so that the pin shape of the crank throw forged product can be formed. Place the forged blank with the convex part facing downward, with the center of the distance between the sides of the main die and the longitudinal center of the forged blank, and pressurize the punch to remove the forged blank. bend.

When the convex portion of the forged blank hits the back chamfer regulating die, extra thickness is produced in the vicinity of the punch of the forged blank. Next, the punch punches the convex part of the forged rough ground back into the chamfer regulation mold.
The area around the push pin is molded into the space made up of the side regulating mold and anvil. At this time, the back chamfer regulating die acts as a resistance against deformation, so tension is generated near the punch, eliminating excess metal, and the amount of material movement in the forging rough area on the opposite side of the punch is reduced, preventing material shortages. .

(Example) Examples of this invention are shown in FIGS. 1 to 7.

First Example〉 Figures 1 to 5 are part 3 of the back chamfer of crank throw.
This device is used for molding the back chamfer side portion 4, and is equipped with a main mold 31 having a U-shaped recess opening at the top.

A pair of back chamfer regulating molds 32 having a shape corresponding to the shape of the back chamfer portion 3 of the crank throw are attached to opposite inner surfaces of the main mold 31, respectively. A pair of side surface regulating molds 33 having opposing surfaces corresponding to the back chamfer side surface portions 4 of the crank throw are attached to the inner surfaces of both back chamfer regulating molds 32. The side regulation mold 33 provided on one back chamfer regulation mold 32 and the side regulation mold 33 provided on the other back chamfer regulation mold 32 are spaced apart from each other by an interval that allows the punch 5 to be press-fitted. They are facing each other. An anvil 34 having a shape corresponding to the shape of the pin on the piston side of the crank throw is protruded from the bottom of the concave portion of the main mold 31 at the center between the puff chamfer regulating molds 32 and 32. As shown in FIGS. 4 and 5, a punch 35 having a shape corresponding to the shape of the pin on the journal side of the crank throw faces the anvil 34 and can enter the recess in the main mold 31. It is provided. The thickness of the tip of the punch 35 is equal to the web spacing of the forged product, and the portion above the top of the semicircular recess corresponding to the pin shape is thickened with a tapered portion 36 interposed therebetween.

The procedure for forging an assembled crank throw using this apparatus will be explained with reference to FIGS. 6 and 7.

Plume 38 from ingo throat 37 using a forging press
Manufacture. A forged rough ground 39 having a convex cross section in the longitudinal direction is produced from this bloom using a forging press. The forged rough area 39 is installed with the convex portion facing downward so that the center of the recess of the main mold 31 and the longitudinal center of the forged rough area 39 coincide with each other, and the punch 35 is pressurized to insert the forged rough area 39. Subsequently, when the convex part of the forged rough ground 39 hits the back chamfer regulation mold 32, the punch 35 punches the convex part of the forged rough ground 39 by the back chamfer regulating mold 32, the side regulating mold 33, and the anvil 34. The pin 2 of the crank throw and the area around the pin are molded by being pushed into the space. The forged rough material 39 that has been molded is taken out from the mold 31, and a medium plate with the same thickness as the finished web interval is placed between the webs 1 and pressed down to the finished web thickness using the anvil of a forging press. As a result, assembled crank throw forged products can be formed.

<Second Example> Figures 8 to 9 show back chamfer part 3 of crank throw.
It is a device used when molding a crank throw, and is equipped with a main mold 31 having a U-shaped recess, and a mold in the shape of a back chamfer part 6 of a crank throw on both inner surfaces of the recess of the main mold 31. A pair of puncture-chamfer regulating molds 32 having corresponding shapes are provided to face each other, and the back-chamfer regulating molds 32 are installed at a distance that allows the punch 5 to be press-fitted, and are attached to the pin 2 of the crank throw. An anvil 34 having a shape corresponding to the shape is attached to the center of the bottom surface of the recess of the main mold 31. A punch 35 having a semicircular recess formed at its tip corresponding to the shape of a crank throw pin faces the anvil 34 and can be press-fitted between both back chamfer regulating molds 32.

The procedure for forging an assembled crank throw using this device will be explained with reference to FIG. 10. A bloom 38 is produced from the ingot 37 using a forging press. The process of producing a forged rough ground 39 having a convex longitudinal section from this plume using a forging press is the same as in the first embodiment described above.

The forged rough area 39 is installed with the convex portion facing downward so that the center of the recess of the main die 31 and the longitudinal center of the forged rough area 39 coincide with each other, and the punch 35 is pressurized to push the forged rough area 39. .

Subsequently, when the convex part of the forged rough ground 39 hits the back chamfer regulation mold 32, the punch 35 hits the convex part of the forged rough ground 39,
The pin 2 of the crank throw and the pin periphery are molded by being pushed into the space formed by the back chamfer regulating mold 32 and the anvil 34. The forged raw material 39 that has been molded is taken out of the mold 31, and a middle plate with the same thickness as the finished web spacing is placed between the webs and pressed down with the anvil of a forging press to the finished web thickness. Assembled crank throw forged products can be formed.

(Effect of the invention) In the conventional method, wrinkles and shrinkage occurred, so the 14th
As shown in the figure, extra thickness was added to ensure the product even if wrinkles occurred, but with the method according to this invention,
Yields are improved and machining time is shortened because excess metal is not needed.

In the conventional method, the pin 2 is formed, but the precision around the pin is poor, so there is a lot of excess material.However, with the method of the present invention, the pin 2 and the surrounding area can be die-forged to nearly the product shape. Yields are improved, cutting time is also shortened due to less cutting allowance, and since the forged shape is close to the product shape, positioning for machining can be done easily. The yield improvement according to the present invention is 10% or more compared to the conventional method.

[Brief explanation of drawings]

Fig. 1 is a front view of a mold showing the first embodiment of the present invention;
The figure is a sectional view taken along the line nn of Fig. 1, Fig. 3 is a perspective view of the same, and Fig. 4 is a sectional view taken along line nn of Fig. 1.
Figure 5 is a front view of the punch, Figure 5 is a side view of the same, Figure 6 is a process diagram showing the manufacturing process of rough ground, Figure 7 is a process diagram showing the partial die forging method, and Figure 8 is the process diagram of the present invention. A front view of the mold showing the second embodiment, FIG. 9 is a perspective view of the mold, FIG. 10 is a process diagram of the same, and FIG.
Figure 1 is a perspective view of a crank throw showing the names of each part of the crank throw, Figure 12 is a process diagram showing the conventional method, Figure 13 is a process diagram showing the conventional method, and Figure 14 is a process diagram showing the conventional method. FIG. 3 is an explanatory diagram showing a crank throw. 2... Crank throw pin part, 3... Back chamfer part, 4... Back chamfer side part, 31
...Main mold, 32...Bafuku Chamfer fflI
II mold, 33... side regulation mold, 34... anvil, 35... punch. Patent applicant: Kobe Steel, Ltd. Figure 12

Claims (1)

[Claims] 1. A method for partially inserting and forging a crank throw, characterized in that the pin portion of the crank throw and the web portion around the pin are forged while being restrained by a die. 2. A device for partially inserting and forging the peripheral part of the pin 2 of a crank throw, which is equipped with a main mold 31 having a U-shaped recess, and on both inner surfaces of the U-shaped recess of the main mold 31, Back chamfer regulation molds 32 each having a shape corresponding to the shape of the back chamfer part 3 of the crank throw are provided in an opposing manner, and a punch 35 is provided which is press-fitted between the regulation molds 32 so as to be freely insertable and removable. The crank throw partial die forging device is characterized in that the punch 35 is formed in a shape corresponding to the pin shape of the crank throw. 3. A device for partially inserting and forging the peripheral part of a crank throw pin, which includes a main mold 31 having a U-shaped recess, and a crank provided oppositely on both inner surfaces of the recess of the main mold. A pair of back chamfer regulating molds 32 having a shape corresponding to the shape of the back chamfer portion 3 of the throw, and a crank throw provided at a distance that allows a punch 35 to be press-fitted into the inner surface of both back chamfer regulating molds. a pair of side regulating molds 33 having opposing surfaces corresponding to the back chamfer side portions 4 of the main mold; and an anvil 34 having a shape corresponding to the shape of a crank throw pin provided in the center of the recess of the main mold. A partial die forging device for a crank throw, comprising a punch 35 that is press-fitted opposite the anvil 34 and has a shape corresponding to the shape of a pin of the crank throw.