KR20190047910A - Manufacturing method of crankshaft and crankshaft manufactured by the same method - Google Patents

Abstract

The present invention relates to a manufacturing method of a crankshaft and a crankshaft manufactured by the same which can manufacture a crankshaft by a non-twist forging method. The manufacturing method of a crankshaft comprises: a first process of inserting a material heated to a prescribed temperature between an upper mold and a lower mold to distribute a volume; a second process of pressing the material in the upper mold and the lower mold to perform preliminary forming; a third process of pressing the material which has undergone the second process in the upper mold and the lower mold to perform final forming; and a fourth process of removing burrs of the crankshaft material which has undergone the third process to complete forming of a crankshaft. Forming of the crankshaft which has undergone the first to the fourth process is completed in a state where setting of the phase angle of a crank pin is completed.

Description

Technical Field The present invention relates to a crankshaft manufacturing method and a crankshaft manufactured by the manufacturing method,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft manufacturing method and a crankshaft manufactured by the manufacturing method. More particularly, the present invention relates to a crankshaft manufacturing method capable of manufacturing a crankshaft by a non- To a crankshaft.

The crankshaft of the vehicle is a part that converts the reciprocating motion of the engine piston into rotational motion. The crankshaft serves as a main shaft, a crank pin to which the big end of the connecting rod connecting the crank is mounted, And an annular counterweight attached to the end of the crank arm.

The shape of the counterweight is a shape in which the joint portion is small and becomes larger and thicker as going forward, and has a shape for increasing the inertia force even when the same weight is rotated. The counter weight is inflated by the piston, so that the piston, the connecting rod, and the crankshaft are integrated so that a large inertia force does not act when rotating.

Since the reciprocating engine rotates the crankshaft via the connecting rod every time the piston performs the expansion stroke, it is reliably supported by the journal, but complicated bending and torsion acts. For this reason, the crankshaft requires special rigidity and is produced by forging and casting of steel. A method of manufacturing such a crankshaft is disclosed in Korean Patent Registration No. 10-1645086.

In the above-described method of manufacturing a crankshaft, twist and coining processes for rotating both ends of the crankshaft in different directions are necessary after the forging process for pin-phase angle forming at intervals of 120 degrees. However, the material of the crankshaft is deformed during the twist process, resulting in defective products, and the manufacturing process is complicated, which causes the production cost to increase.

Korean Patent Registration No. 10-1645086 (Registered on July 27, 2016)

An object of the present invention is to provide a method of manufacturing a crankshaft capable of manufacturing a crankshaft by a non-twist method and a crankshaft manufactured by the method.

A method for manufacturing a crankshaft according to the present invention is a method for manufacturing a crankshaft comprising a first step of distributing a volume by inserting a material heated to a predetermined temperature between an upper mold and a lower mold, 2, a third step of press-molding the material through the second step in the upper mold and the lower mold, and a third step of molding the crankshaft by removing the burrs of the crankshaft material through the third step And the fourth step of completing the molding of the crankshaft, wherein the crankshaft having undergone the first to fourth steps is completed with the phase angle setting of the crank pin completed.

The upper mold and the lower mold are vertically asymmetric.

The crankshaft is a three-cylinder crankshaft having first to third crankpins and a plurality of counterweights, and the crankpins are arranged to have a phase angle of 120 degrees with respect to each other.

And the upper mold and the lower mold are formed such that a parting line is formed so as to pass through the center of the upper mold portion and the lower mold portion of the crank pin and the counterweight with reference to the first and third crank pins.

The upper mold and the lower mold are formed such that the parting line passing through the center of the crankpin and the center of the counterweight is stepped.

And the upper mold and the lower mold are formed such that a parting line is formed so as to pass through the center of the upper portion and the lower portion of the crank pin with reference to the second crank pin.

Further, the present invention is a crankshaft manufactured by the method of manufacturing a crankshaft according to any one of claims 1 to 6, wherein the crankshaft includes an upper mold portion disposed in the upper mold and a lower mold portion disposed in the lower mold A plurality of crank pins each having a crank journal as a main shaft and a big end of a connecting rod connecting a crank of the engine and having a phase angle with respect to each other; And a plurality of counterweights provided at the ends of the crankpins, wherein the upper and lower parts are formed to have asymmetric parting lines.

And the crankshaft is provided with a light weighted portion (A) in which the crank pin is separated from the counterweight.

And the weighted portion is formed in a direction perpendicular to the central axis of the crankshaft.

And the crankshaft is provided with a reverse gradient shape removing portion B on the side of the interface between the upper crank pin and the crank pin, and on one side of the left and right crank arm ends of the first and third crank pins.

The crankshaft manufactured by the manufacturing method of the crankshaft according to the embodiment of the present invention and the crankshaft manufactured by the manufacturing method of the crankshaft are manufactured by the non-twist method forging method, And the forging quality can be improved. In addition, since the manufacturing process is reduced to four processes in the existing six processes, the productivity is improved and the manufacturing cost is reduced.

1 is a schematic view showing a forging process in a method of manufacturing a crankshaft according to an embodiment of the present invention;
FIG. 2 is a schematic view showing upper and lower molds according to FIG. 1,
FIG. 3 is a schematic view showing a combined state of the upper and lower dies according to FIG. 2,
FIG. 4 is a schematic view showing a section view according to each section of FIG. 3;
5 is a perspective view illustrating a crankshaft manufactured by a method of manufacturing a crankshaft according to an embodiment of the present invention,
6 is a view showing the crank pin position of the crankshaft according to FIG. 3,
Figure 7 shows the features of the crankshaft according to Figure 3,
FIG. 8 is a schematic view showing a reverse gradient position of a mold according to the shape of a general crankshaft,
Fig. 9 is a schematic diagram showing a reverse gradient shape removal position of the crankshaft according to Fig. 5;

Hereinafter, a method of manufacturing a crankshaft according to an embodiment of the present invention and a crankshaft manufactured by the method will be described in detail with reference to the drawings (hereinafter, referred to as a three-cylinder crankshaft as a reference, However, the same method can be applied to 5, 6, and 8 cylinder crankshafts with different crank pin phase angles).

In general, the forging process of a crankshaft is a forging process of a four-cylinder crankshaft in which the phase angle of the crankpin is located at a 0 ° and 180 ° symmetrical plane, and a forging process in which the phase angle of the crankpin is 3, 5, 6, 8 cylinder crankshaft forging process.

The four-cylinder crankshaft does not require a twist and coining process, but a twist and coining process is essential for 3, 5, 6, and 8-cylinder crankshafts.

In the case of a forging process requiring a twist and a coining process, the material is heated for a predetermined period of time, usually by hot forging. The material (for example, 1230 degrees centigrade) heated to a predetermined temperature is divided into upper and lower dies a step of molding a crankshaft preparation (an article being manufactured) through a buster (first step), a preliminary molding (blocker) and a final molding (finisher), and then removing a protruding burr (trimming, fourth step). Thereafter, the crankshaft is inserted into the twist mold and rotated to form the phase angle of the crank pin (twist process), and the phase angle of the formed crank pin is corrected (coining process) to complete the crankshaft.

However, the present invention proposes a method for manufacturing a crankshaft and a crankshaft therefor, which can eliminate the twisting process and the coining process by forming the phase angle of the crank pin in the forging process by changing the design of the mold.

1 is a schematic view showing a forging process in a method of manufacturing a crankshaft according to an embodiment of the present invention.

As shown in FIG. 1, the method of manufacturing a crankshaft according to an embodiment of the present invention can produce an end crankshaft product through a four step forging process of a buster process, a blocker process, a finisher process, and a trimming process. The crankshaft is arranged with the crank pin phase angle being 120 degrees apart only forging process.

Fig. 2 is a schematic view showing upper and lower dies according to Fig. 1;

As shown in FIG. 2, in the crankshaft manufacturing method of the present invention, the upper and lower molds 10 and 30 used in the first to fourth processes have an asymmetric structure. This is for forming the phase angle between the crank pins of the crankshaft through only a forging process without a separate twist process.

The mold design was improved by analyzing the part of the mold crankshaft contact with the mold and the part which is not in contact with the mold according to the gap between the upper mold (10) and the lower mold (30) and the molding load. In addition, based on the result of the forming analysis by dividing the case where the molding load is insufficient and the case where the molding load is insufficient at each step, the meat part is found and a proper molding load is derived. Based on these experiments, it is possible to reduce the excessive molding load by increasing the volume of the crankshaft forming part in the first step (less than 2,000 tons), reducing the gap between the upper mold and the lower mold in the second step And the optimum design of the mold was derived.

FIG. 3 is a schematic view showing a combined state of the upper and lower molds according to FIG. 2, and FIG. 4 is a schematic view showing a section view according to each section of FIG.

3, in a state in which the upper mold 10 and the lower mold 30 are coupled to each other, a section view of each of the sections A, B, and C is shown. As shown in FIG. 4, three crank pins 110 Are arranged to have a phase angle of 120 degrees each.

Section A is adjacent to the first crank pin 110 adjacent to the center axis (meaning one end axis of the crankshaft) of the crankshaft (to be described later) (to be described later), section B is adjacent to the second crank pin 110 , And section C is in the vicinity of the third crank pin 110.

The upper mold 10 and the lower mold 30 are formed such that a parting line (an imaginary line 106 forming a boundary between upper and lower molds) is formed on the upper side of the crankpin 110, (Between the upper and lower mold portions), and is formed such that the parting line 106 passes through the center of the counterweight with reference to the counterweight after being bent. At this time, the first crank pin 110 is located on the right side with respect to the section A.

The upper mold 10 and the lower mold 30 are formed such that the parting line 106 passes through the center of the upper mold portion and the lower mold portion of the crank pin 110 with reference to the second crank pin 110. At this time, the second crank pin 110 is located at the lower portion with respect to the section B, and the counterweight is located at the upper portion, and the parting line 106 does not pass.

Finally, the parting line 106 passes through the center of the upper portion and the lower portion of the crank pin 110 on the basis of the third crank pin 110, As shown in FIG. At this time, the third crank pin 110 is located on the left side with respect to the section C.

The upper mold 10 and the lower mold 30 are vertically asymmetric and the crank pins 110 are arranged to have a phase angle difference of 120 degrees with each other in the mold. The upper and lower molds 10 and 30 are different from each other. Therefore, the crank pins 110 can be arranged so as to have a phase angle of 120 degrees with each other without a twist process only in the mold. It is also possible to manufacture a crankshaft having a different angle of phase angle by designing the mold on the same principle.

Hereinafter, a crankshaft manufactured by the crankshaft manufacturing method of the present invention will be described.

FIG. 5 is a perspective view of a crankshaft manufactured by a method of manufacturing a crankshaft according to an embodiment of the present invention, and FIG. 6 is a view illustrating a crank pin position of the crankshaft according to FIG.

As shown in FIGS. 5 and 6, the three-cylinder crankshaft 100 can be divided into an upper portion 102 disposed in the upper mold 10 and a lower portion 104 disposed in the lower mold 30 Three crank pins 110 having a phase angle of 120 degrees with each other, a plurality of counterweights 170 disposed below the crank pins 110, a plurality of crank journals 130, And a crank arm (150). The crank journal 130 becomes the main shaft, and the big end of the connecting rod connecting the crank of the engine is mounted on the crank pin 110. The crank arm 150 connects the crank pin 110 and the counterweight 170 is integrally formed at the end of the crank arm 150.

The parting line 106 is formed to asymmetrically cross the upper and lower mold sections 102 and 104 which are not the center of the upper mold section 102 and the lower mold section 104 as described in the above description of the mold.

When the mold is designed so that the second crank pin 110 is located at the 6 o'clock position (the lower side in Fig. 6), the crankshaft 100 can be forged without a twist process with minimum shape change based on Fig. Also, as in the above-described mold description, it is preferable that the contour line and the parting line coincide with each other when viewed from the direction of the second crank pin 110 and the direction opposite thereto.

On the other hand, in the crankshaft of the present invention, it is necessary to secure a sufficient weight on the outside in the radial direction in order to sufficiently secure the function of the counterweight.

Fig. 7 is a view showing a characteristic portion of the crankshaft according to Fig. 3;

7, the weight of the crankpin 110 and the counterweight 170 may be made lighter (the same shape as that obtained by losing the material of the corresponding portion) in order to secure a sufficient weight of the counterweight 170 have. The weighted portion A is preferably formed at a portion corresponding to the position of the main shaft (crank journal) of the crankshaft 100. The crank pin 110 and the counterweight 170 corresponding to the box- Lt; / RTI > It is preferable that the shape of the lightened portion A is formed in a vertical direction (a direction perpendicular to the central axis with reference to Fig. 7) so as not to cause an undesirable deformation.

FIG. 8 is a schematic view showing a position of a backward gradient of a mold according to a shape of a general crankshaft, and FIG. 9 is a schematic diagram showing a position where a backward gradient shape of the crankshaft is removed according to FIG.

As shown in FIG. 8, there is a portion where a reverse gradient shape occurs in the design of the mold during forging of the crankshaft. The part where the backplane is generated occurs at the part where the shape of the product is larger than the entrance of the mold, which is a common problem in the forging method. If an inverted embryo is generated, a meat part is generated and a product failure occurs.

In order to solve such a problem, according to the present invention, as shown in FIG. 9, a reverse gradient portion on which a backward displacement may occur on the crankshaft 100 is removed, thereby preventing defective product due to a reverse gradient. The reverse gradient shape removal area (B) is indicated by a dotted line in FIG. The reverse gradient shape removal area B can be realized by changing the shape of the part protruding largely from the entrance on the mold to a straight shape or changing the shape to have a width coinciding with the entrance on the mold.

The upper mold 10 may be disadvantageously displaced by the parting line 106 toward the upper surface of the upper mold 10 on the side of the second crank pin 110. In the case of the first and third crank pins 110, A backward displacement may occur at one side of the end of the crank arm 150. [ Therefore, the reverse gradient problem can be solved by removing the reverse gradient shape portion.

One embodiment of the present invention described above and shown in the drawings should not be construed as limiting the technical spirit of the present invention. The scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can improve and modify the technical spirit of the present invention in various forms. Accordingly, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

10: upper half 30: lower half
100: crankshaft 102:
104: lower portion 106: parting line
110: crank pin 130: crank journal
150: Crank arm 170: Counterweight
A: lightweight portion B: reverse gradient portion

Claims (10)

A first step of inserting a material heated to a predetermined temperature between an upper mold and a lower mold to distribute the volume,
A second step of preliminarily molding the material in the upper mold and the lower mold,
A third step of press-molding and finally molding the workpiece passed through the second step in the upper mold and the lower mold,
And a fourth step of completing the crankshaft molding by removing the protruding burr of the crankshaft stock prepared through the third step,
Wherein the crankshaft having been subjected to the first to fourth steps is completed with the phase angle setting of the crank pin being completed. The method according to claim 1,
Wherein the upper mold and the lower mold are vertically asymmetric. 3. The method of claim 2,
Wherein the crankshaft is a three-cylinder crankshaft having first to third crankpins and a plurality of counterweights, and the crankpins are arranged to have a phase angle of 120 degrees with respect to each other. The method of claim 3,
Wherein the upper mold and the lower mold are formed such that a parting line is formed so as to pass through a center of a top portion and a bottom portion of the crank pin and the counterweight with reference to the first and third crank pins. 5. The method of claim 4,
Wherein the upper mold and the lower mold are formed such that the parting line passing through the center of the crank pin and the center of the counterweight is stepped. 6. The method of claim 5,
Wherein the upper mold and the lower mold are formed such that a parting line extends from a center of an upper portion and a lower portion of the crank pin with respect to the second crank pin. A crankshaft manufactured by the method for manufacturing a crankshaft according to any one of claims 1 to 6,
Wherein the crankshaft is divided into an upper mold portion disposed in the upper mold and a lower mold portion disposed in the lower mold, a crank journal serving as a main shaft, and a big end of a connecting rod connecting the crank of the engine, A plurality of crank pins having a phase angle, a crank arm connecting the crank journal and the crank pin, and a plurality of counter weights provided at the end of the crank pin,
Wherein the upper and lower mold parts are formed to have an asymmetric parting line. 8. The method of claim 7,
Wherein the crankshaft comprises a lightweight portion (A) that is worn between the crank pin and the counterweight. 9. The method of claim 8,
And the weighted portion is formed in a direction perpendicular to the center axis of the crankshaft. 8. The method of claim 7,
Wherein the crankshaft has a backward gradient eliminating portion (B) at an interface between the upper end of the upper crank pin and the left and right crank arm ends of the first and third crank pins.

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