JPH0520181B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides that, of both axial surfaces of the crank arm, the outer surface to which the crank journal is connected is
It has a notched shoulder drop at the end on the crankpin side in the radial direction, and the inner surface to which the crankpin is connected has a concave hollowed out part on the journal side in the radial direction. 3-cylinder, 6-cylinder or V-type 12 cylinders with crank pins arranged at 120° intervals in the rotational direction
The present invention relates to a method for forging an integral crankshaft for a cylinder.

(Prior art and its problems) Conventionally, when forging a 6-throw, 120° interval type integral crankshaft for an in-line 6-cylinder, for example, if a shoulder drop part is provided on the crank arm to reduce weight, the crankshaft Since the arm center line and the forging die dividing basic line intersect at a 30° angle,
It is not possible to stamp and forge the crank arm into a shape that is substantially symmetrical with respect to the crank arm centerline.

Therefore, it is not possible to manufacture a crankshaft with good dynamic balance only by forging, and it is necessary to separately machine a relatively large balance hole. Also, the geometric balance is not good, so
There is also a problem with rigidity.

(Object of the Invention) An object of the present invention is to provide a method for forging an integral crankshaft, in which the crank arm can be die-forged into a shape symmetrical with respect to the crank arm center line. It is said that

(Structure of the Invention) (1) Technical Means The present invention provides an outer surface to which the crank journal 10 is connected, of both surfaces in the axial direction of the crank arm 14 that integrally connects the crank journal 10 and the crank pin 12 eccentric therefrom. has a notch-shaped shoulder drop portion 18 at the end on the crankpin side in the radial direction.
The inner surface to which the crank pin 12 is connected has a hollowed out portion 20 that is concave on the journal side in the radial direction.
Some of the crank arms have
A balance weight 16 is integrally provided on the opposite side in the radial direction, and the crank pin 12 for each cylinder is rotated in the rotation direction.
In the forging method of an integrated crankshaft for 3 or 6 cylinders arranged at 120° intervals, the balance weight 16 and the integrated crank arm 14 are prerequisite for setting the parting line which becomes the mating surface of the upper and lower forging dies. A forging die dividing basic line 02 inclined by 30 degrees is set with respect to the center line 03 of Reference lines 22 and 24 separated by A parallel line 26 passing through point 03 and parallel to base line 02 is set, and the intersection of this parallel line 26 and the reference line 24 on the inner side is set as the inner reference point Q. Then, on the outer surface of the crank arm, set the base line 26. 02 and the outer surface side reference point P and the parallel line 26 are set as mold dividing lines, and on the inner surface, an inner surface connecting line 30 connecting the parallel line 26, the inner surface side reference point Q, and the mold dividing basic line 02 is set. Then, set the mold dividing basic line 02 on the inner surface side as the mold dividing line, and then mold cutting lines 32, 34 extending from the respective reference lines 22, 24 of the shoulder drop part 18 and the lightening part 20 to the side surface of the crank arm 14. , positions that are approximately symmetrical across the crank arm center line 01 with respect to the reference points P and Q on both sides are defined as symmetrical reference points P' and Q', and these symmetrical reference points P' and Q' and the reference points P, Die-cutting lines 32 and 34 extending from Q to the reference lines 22 and 24 at angles θ1 and θ2 that allow die-cutting that are larger than 30° are set, and the die-cutting lines on the outside side and the die-cutting line on the inside side are set. Forging of an integral crankshaft that is forged so as to form a thick-walled area D that is approximately symmetrical in an octagonal shape with the overlapping locus area C of the journal 10 and the crank pin 12 as the center, using the line and each die-cut line 32, 34. It's a method.

(Example) In FIG. 1 showing a six-throw 120° interval crankshaft for an in-line six-cylinder diesel engine manufactured according to the present invention, 10 is a crank journal, and 12 is a crank pin. The crank journal 10 and the crank pin 12 are connected by a crank arm 14, and a balance weight 16 is continuous with the crank arm 14.

As shown in FIG. 2, which is an enlarged view of the main part of FIG. 1, the crank arm 14 is formed with a shoulder drop portion 18 and a lightened portion 20 for weight reduction. The center line 01 of the crank arm 14 and the forging die dividing basic line 02 are at an angle of deviation θ (θ=30°) as shown in Fig. 3.
It's only leaning. Center line 01 is crank pin 12
The basic line 12 passes through the center line 03 of the crank journal 10 and the center line 04 of the crank journal 10, and the basic line 12
Only passing through. In addition, the mold division basic line is
This refers to the basic die dividing line in die forging determined by the crank arrangement.

When punching and forging the above crank arm 14 and balance weight 16, all throws are stamped at the same time using divided forging dies from the directions of arrows A and B perpendicular to the basic line 02. However, in order to form the crank arm 14 in a symmetrical shape with respect to the center line 01, the dividing line of the forging die is set as follows.

That is, distances h1 and h2 (h1=
h2) across the reference line 22 (crank arm 14
along the reference line 24 (inner surface side of the crank arm 14), shoulder drop portion 18, and lightened portion 20.
The upper and lower edges of are formed. A reference point P, which is an intersection with the basic line 02, is determined on the reference line 22. Also, on the reference line 24 is a parallel line 26 that is parallel to the basic line 02 and passes through the crank pin center 03.
has been set, and a reference point Q, which is the intersection of the parallel line 26 and the reference line 24, has been determined. Further, if the intersection of the parallel line 26 and the upper edge of the crank arm 14 is R, then R and the reference point P are connected by an outer surface connecting line 28. Note that the mold dividing line is continuous on R in the direction perpendicular to the plane of the paper. Therefore, on the outer surfaces of the crank arm 14 and balance weight 16, the mold dividing line is continuous along the center line 02 and the outer surface connecting line 28.

The distances h1 and h2 are determined as follows.
First, assume that h1 is an arbitrary size, determine the intersection P between the reference line 22 and the basic line 02, then determine the die cutting line 32 inclined by θ1 from the intersection P, and similarly form the die from h2. The extraction line 34 is determined.

L is determined by these factors, and h1 is determined so that L is 50% to 100% of the maximum thickness T of the crank arm 14.

On the inner surfaces of the crank arm 14 and the balance weight 16, the reference point Q and the basic line 02 are connected by an inner surface connection line 30 that is generally parallel to the outer surface connection line 28. Therefore, on the inner surface side, a mold dividing line is formed by the parallel line 26, the inner surface connection line 30, and the basic line 02.

Symmetrical reference points P' and Q' that are symmetrical to the reference points P and Q across the center line 01 have been determined, and the angles θ1 and θ2 from these reference points P, Q and symmetrical reference points P' and Q' are determined. The die cutting lines 32 and 34 are extended. θ1 is set to 40°, which is larger than θ, and θ2 is also set to 35°. Therefore, when the die is stamped along the arrows A and B perpendicular to the basic line 02, the die is easily cut out. The ends of the die-cut lines 32, 34 are continuous with the side surface 36 of the crank arm 14 within a length L.

Furthermore, in the crank arm 14, the reference line 22 and die cut line 32 on the outer surface side and the reference line 24 and die cut line 34 on the inner surface side are connected at both side surfaces 36, and an overlapping trajectory range C is formed.
The shoulder drop part 1 is in the range D (hatched with two-dot chain line) that forms a geometrically symmetrical octagon with
8. A portion without lightening by the lightening part 20 is formed.

In the crank arm 40 where the balance weight 16 is not provided, a die dividing line 42 is set as shown in FIGS. , The pattern is stamped from the F direction.

A manufacturing method by forging a crankshaft will be explained. When forging the crank arm 14 and balance weight 16 of the above-mentioned crankshaft, first preheat the crank arm 14 and balance weight 16, and use a forging die divided by the above-mentioned die dividing line to form the arrows A, Punch from direction B.

This mold dividing line is formed along the basic line 02 and the external connecting line 28 on the outside side, and along the parallel line 26, the internal connecting line 30, and the basic line 02 on the inside side, so the forging mold dividing basic line Even in the case of a crankshaft where 02 is inclined by θ with respect to the center line 01 of the crank arm 14, the crank arm 14 provided with the shoulder drop portion 18 and the cutout portion 20 can be made approximately symmetrical with respect to the center line 01. During formation, the balance weight 16 is also forged integrally. Therefore, the dynamic balance of the crank arm 14 is improved.

In addition, in the crank arm 14, the overlapping trajectory range C
Since the crank arm 1 is formed in an octagonal range D that is approximately symmetrical with the part without hollowing out centered on
4 is maintained, and the crank arm 14 has strong rigidity.

(Effects of the Invention) As explained above, in the method for forging an integral crankshaft according to the present invention, the crank arm 14
Even if the center line 01 of the forging die and the forging die dividing basic line 02 determined by the crank arrangement are inclined, the forging die dividing line should be along the basic line 02 on the outer surface and the outer connecting line 28, and on the inner surface parallel to the basic line 02. 26. Since the inner connecting line 30 is set along the basic line 02, the crank arm 14 can be moved symmetrically with respect to the center line 01 while forming the shoulder drop part 18 and the lightening part 20 on the crank arm 14. In addition, the crank arm 14 and balance weight 16 can be integrally forged.

In particular, the reference points P,
Since the symmetry reference points P' and Q' are set, the geometrical symmetry of the crank arm 14 can be maintained, and the rigidity of the crank arm 14 can be increased to improve its strength.

Furthermore, since the die cutting lines 32 and 34 are set at angles θ1 and θ2 that are larger than θ, the forging die that is divided along the above-mentioned die dividing line is stamped along the arrows A and B. It can also facilitate die cutting.

(Another Embodiment) (1) The present invention is not limited to a crankshaft with 6-throw crank pins at 120° intervals as described above, but can also be applied to a crankshaft with 3-throw crankpins at 120° intervals.

[Brief explanation of the drawing]

FIG. 1 is a front view of a crankshaft manufactured according to the present invention, FIG. 2 is an enlarged view of the main part of FIG. −
The sectional view, FIG. 5, is a view taken in the direction of the arrow in FIG. 10... Crank journal, 12... Crank pin, 14... Crank arm, 16... Balance weight, 18... Shoulder drop part, 20... Lightening part, 22, 24... Reference line, 32, 34... ...Mold cutting line, 01...Crank arm center line, 02
...Forging die division basic line, P, Q...Reference point,
P′, Q′…symmetrical reference points.

Claims (1)

[Scope of Claims] 1 Of both surfaces in the axial direction of the crank arm 14 that integrally connects the crank journal 10 and the crank pin 12 eccentric therefrom, the outer surface to which the crank journal 10 is connected has a crank pin in the radial direction. It has a notched shoulder drop part 18 at the side end,
The inner surface to which the crank pin 12 is connected has a concave hollowed out portion 20 on the journal side in the radial direction, and some of all the crank arms 14 have a balance weight 16 integrated on the opposite side in the radial direction. In preparation for this, the crank pin 12 for each cylinder rotates 120° in the rotation direction.
In the forging method for integral crankshafts that are arranged at intervals, the premise of setting the mold dividing line, which is the mating surface of the upper and lower forging dies, is 30 mm with respect to the center line 01 of the crank arm 14 that is integrated with the balance weight 16. ° An inclined forging die division basic line 02 is set, and a reference line 22 is spaced approximately equal distances (h1, h2) in the direction of the crank arm center line 01 across the overlapping locus range C of the crank pin 12 and crank journal 10. ,24
are set on the outer and inner surfaces of the crank arm 14, and the intersection of the base line 02 and the reference line 22 on the outer surface is set as the outer reference point P, and on the inner surface, the base line 02 passes through the crank pin center point 03. Parallel lines 26 are set, and the intersection of this parallel line 26 and the reference line 24 on the inner side is set as the inner reference point Q. Then, on the outer surface of the crank arm, the reference line 02 and the outer reference point P are set. The outer surface connecting line 28 connecting the parallel lines 26 is set as a mold dividing line, and on the inner surface, an inner surface connecting line 30 connecting the parallel line 26, the inner surface side reference point Q, and the mold dividing base line 02 and the inner side mold dividing base line are set. 02 is set as the die dividing line, and then the reference points P, Positions that are approximately symmetrical to Q across the crank arm center line 01 are defined as symmetrical reference points P and Q, and from these symmetrical reference points P' and Q' and reference points P and Q to reference lines 22 and 24. Die-cutting lines 32 and 34 extending at angles (θ1, θ2) that allow die-cutting larger than 30° are set, and the die-cutting lines 32, 34 on the outer surface side, the die-cutting line on the inner side, and each die-cutting line 32, 34, a method for forging an integral crankshaft, characterized in that the forging is performed so as to form a thick-walled area D that is substantially symmetrical in an octagonal shape with the overlapping locus area C of the journal 10 and the crank pin 12 as the center.