JPS5842776B2 - Manufacturing method of crankshaft for 3-cylinder engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a crankshaft for a three-cylinder engine by a stack molding method.

In general, the crankshafts for three-cylinder engines have their crank pins out of phase by 120 degrees, so when casting them, the dividing surfaces of the mold become complicated, making mold design difficult and a practical problem. As a result, it was considered impractical due to poor workability and expected cost increases.

Therefore, conventionally, in order to solve the above problems, three
As a method of casting a crankshaft for a cylinder engine, a method using a stack molding method has been proposed (see Japanese Utility Model Publication No. 39691/1983).

In other words, for casting a crankshaft for a 3-cylinder engine in which the phase of the crank pin part is shifted by 120 degrees,
A plurality of molds are prepared which are divided so that they can be stacked in the axial direction, and even if each of the molds is shifted at a desired angle in the rotational direction around the shaft (crank journal part), the overall shape of the stacked and integrated molds will always remain constant. The crankshaft castings were cast by the horizontal casting method by giving each mold an external shape that would give the desired shape, assembling the molds in a stacked, one-piece, and placing the assembled molds in the outer mold and pouring the metal. This makes it possible to form an assembled mold in which several sets of molds of the same type are laminated and integrated, making molding of the mold easy.

In this proposal, the axis (crank journal part) is used as a reference, and each mold is rotated around this axis in the rotational direction (
Even if the desired angle is shifted, the overall shape of the integrated mold will always remain constant, so it is impossible to form a sprue that penetrates the mold.
As a practical matter, there is a drawback in that the only option is to provide sprues, runners, etc. in the upper and lower molds.

In general, vertical casting of crankshafts is a big problem in practical terms, as compared to horizontal casting, there are fewer feeders and the like, resulting in better yields and fewer defects such as slag.

In addition, the production efficiency is limited to one crankshaft for a three-cylinder engine, which is disadvantageous.

The present invention is an epoch-making manufacturing method devised in view of the above, in which cavities of a plurality of molds divided into layers so as to be stackable in the axial direction are positioned at 120 degree intervals on a pitch circle, and are arranged adjacent to each other. Three cavities formed in such a relationship that the phases of the matching cavities shift by 120 degrees around the crank journal when the paper rotates 120 degrees in a fixed direction around the center of the mold are considered one set, and two sets are formed. By doing so, it is an object of the present invention to provide a manufacturing method capable of manufacturing a crankshaft casting for a three-cylinder engine using six cast members.

That is, the present invention is for a three-cylinder engine, and uses a crankshaft whose crank pin portions are out of phase by 120 degrees.
A plurality of molds divided into layers in the axial direction for main cutting are prepared, and the cavities of each mold are located at intervals of 120 degrees on the pitch circle, and the phases of the adjacent cavities are the same as that of the mold. 120 in a certain direction around the center
When the paper rotates once, the crank journal part should be centered 1-1 times.
Two sets are formed, with three molds formed in a relationship that is shifted by 20 degrees, and the plurality of molds are
Three molds A each have cavities a of half the wall thickness and the same phase in the crank pin part and both sides t of the crank arm part, and cavities a with half the wall thickness and the same phase in the crank journal part and both sides thereof. Two molds B each have a crank arm cavity b with an offset angle, and one mold each has a crank journal part on the shaft end side and an adjacent half-thick crank arm cavity C or d. C and D, and the above mold A
and mold B are stacked alternately, and the molds C and D are placed on both sides of the assembled mold, and six crankshaft castings are cast by pouring the metal into the cavity of this assembled mold. It is something.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows a crankshaft mold S for a three-cylinder engine used in a first embodiment of the method of the present invention.

In FIG. 1, reference numeral 1 denotes a crankshaft for a three-cylinder engine, and the crankshaft 1 has a crank journal portion 2 disposed on the same axis, and a phase shift of 120 degrees around the crank journal portion 2. It consists of three crank pin parts 3.3.3 arranged in a staggered manner, and a crank arm part 4.4 that connects the crank pin parts 3 and the crank journal part 2, and the crank arm part 4 is equipped with a balance weight. A section 5 is provided.

The crankshaft mold S is for increasing the number of crankshafts 1 for the three-cylinder engine by six, and is made of a plurality of at least seven pieces, the first to seventh pieces, which can be stacked in the axial direction. The molds 11 to 17 are assembled into a stacked integral state, and the crankshaft XI for the three-cylinder engine is connected to the assembled mold in the axial direction (stacked direction).
Two sets (six in total) of three cavities Q each having a shape corresponding to the above are formed.

Pouring the assembled mold (crankshaft mold S) into each cavity Q as it is in the vertical casting position K, or placing the assembled mold in a halved outer mold and closing the outer mold, Six crankshaft castings are cast by placing the mold in a vertical casting position and pouring the metal through a sprue provided in the center of the assembled mold.

That is, the first part constituting the crankshaft mold S is
~The seventh molds 11 to 17 are each formed into a disk shape with the same diameter, and are attached to the crankshaft 1 and the rank arm portions 4, 4.
... is divided in the axial direction using the dividing plane near the middle.

As shown in FIGS. 2 to 8, the cavities of each mold 11 to 17 are located at intervals of ζ120 degrees on the pitch circle.
The three parts are formed in such a relationship that when rotated in a fixed direction, for example 120 degrees clockwise, around the center O of 7, they shift by 120 degrees counterclockwise around the crank journal part 2. Two sets are formed on different pitch circles with a phase shift of 180 degrees with respect to the mold center O, for example.

Of the first to seventh molds 11 to 17, the second mold.
The fourth and sixth three molds 12, 14 and 16 each have half the wall thickness and the same thickness on both sides of the cavity a3 of the crank pin portion, as shown in FIGS. 3, 5 and 7. Phase crank arm section and balance weight section (hereinafter simply referred to as crank arm section)
The molds A1 are of the same type and have a total of six cavities a consisting of cavities a4ya4, and the third and fifth molds 13 and 15 are, as shown in FIGS. 4 and 6, respectively. Cavity b2 of the crank journal part and cavity b4 of the crank arm part, which has half the wall thickness on both sides and is out of phase by 120 degrees.
．． The mold B is of the same type and has a total of six cavities b consisting of b4 and b4.

Furthermore, as shown in FIG. 2), the first mold 11 is
Cavity c2 of the crank journal part on one shaft end side
and a cavity C4 of a half-thick crank arm portion adjacent to the crank journal portion.
7, as shown in FIG. 8, there are a total of six cavities d consisting of a cavity d2 in the crank journal part on the other shaft end side and a cavity d4 in the half-thick crank arm part adjacent to the crank journal part. Motsu mold D1
It is more than that.

Therefore, the three molds A1 and the two molds B1 are stacked alternately, and the molds C1 and Dl are placed on both sides (
By placing each in the mold A), that is, the first to
The seventh molds 11 to 17 are sequentially laminated and assembled to form the assembled mold (crankshaft mold S).

Here, the molds A1 and B1 each have the same shape as the front and back mating surfaces.

In addition, the mold A1 (second, fourth, sixth mold 12,
14, 16), the center angle 1 on the pitch circle of the mold center O
At the 20 degree position, the front mating surfaces 12a and 14a
, 16a has a pair of uneven dowels el, one of which is convex and the other concave,
e2 (in the figure, the convex dowel e1 is indicated by ◎ and the concave dowel e2 is indicated by ○) is also on the back side mating surfaces 12b, 14b, 16b, and when the mold A1 is turned over, the front side mating surfaces 12a, 14a, 16
Front mating surface 12a at the above position so that it is exactly the same as a.
.

A pair of uneven dowels el opposite to 14a and 16a.

e2 is provided.

That is, as shown in FIGS. 3, 5, and 7, the dowel e1 of the front mating surfaces 12a, 14a, and 16a shown in each figure
．． e2 and the back side mating surfaces 12b, 14b, 1 showing each open cut
Dowels 6b and elle2 each have a central angle of 120 degrees, and the unevenness is provided at the same position on the front and back, but in reverse.
Dowel e1. The shapes of the front and back mating surfaces including e2 are the same.

Further, the mold B1 (third and fifth molds 13°15) has a pair of uneven dowels e1. e2
is provided, while on the back side mating surfaces 13b and 15b,
The above-mentioned front side mating surface 13a.

15a, or one side of the dowel, for example, the convex dowel e1, is provided at that position, and the same convex dowel e1 as the dowel on the front mating surface is provided.
When turning over the diameter line l passing through the dowel (l) as the axis of rotation, the other dowel (concave dowel e2)
) is provided with the same dowel (concave dowel e2).

In other words, as shown in FIGS. 4 and 6, the convex dowels e1 on the front mating surfaces 13a and 15a shown in each figure A and the convex dowels e1 on the back mating surfaces i3b and isb shown each time are at the same position 1 on the front and back sides. This is provided on the front side mating surface 13a.

The concave dowel e2 of 15a and the back side mating surface 13b, the concave dowel e2 of 15b are such that the concave dowel e2 of the front side mating surface (or the concave dowel e2 of the back side mating surface) is aligned with the diameter line l passing through the convex dowel e. The dowels e1. The shapes of the front and back mating surfaces including e2 are the same.

Furthermore, as shown in FIG. 2, one side of the mating surface (the mating surface 11b with the second mold 12) of the mold C1 (first mold 11) has the mold AI (second mold 12) and a cavity. A pair of uneven dowels el and e2 are provided so that the dowels coincide with each other, and the mold D1 (seventh mold 17
) as shown in FIG.
A pair of uneven dowels e1. e
2 is provided.

Therefore, as described above, the first to seventh molds 11 to 17 constituting the crankshaft mold S for a three-cylinder engine
is categorized into four types of molds: three molds A1, two molds B0, and one mold each of C1 and Dl, so it is only necessary to prepare four types of molds A0 to D1, and the above molds A1 and B1 are each dowel e
1. Since the shapes of the front and back mating surfaces including e2 are the same, it can be used regardless of whether it is front or back.

As a result, the molds A1 and B1 were simply placed one on top of the other alternately with the concave-convex dowels e1+62 of each mating surface fitting together, and then the molds C1 and Dl were placed on both sides.
By arranging the dowels together and laminating them in one piece, the crankshaft mold S can be easily and accurately assembled.

In particular, if the crank journal parts 2, 2 on both shaft end sides have the same shape on the left and right sides, the molds C1 and Dl become common with cavities of the same shape.
Since the number of molds is 1ζ, it is possible to simplify the assembly of the crankshaft mold S.

The assembly mold (crankshaft mold S) assembled in this way has six crankshaft cavities and sprues, so by pouring the metal into each cavity from the sprues, six crankshaft castings can be made. can be cast at a high yield at one time, making it possible to efficiently manufacture crankshafts for three-cylinder engines.

In addition, when performing horizontal casting using this assembled mold, the sprue portion of each mold can be used as is as a runner.

Moreover, when the assembled mold is assembled, its external shape is always a constant shape (cylindrical), so the mold is easy to handle and can be easily placed in a halved external mold. The casting can be performed by the simplest method, such as vertical casting in this state, and the mold can be easily formed.

Furthermore, by assembling a mold with cavities formed at both ends of the single axis of the assembled mold, standing the entire mold in a vertical casting position, and pressing it down with a weight from above, it is possible to cast the mold without using an outer mold. is possible.

Also, although we have explained that the mold is disc-shaped, the point is that it is sufficient as long as it can maintain the shape necessary to form the cavity or dowel, and a mold with cutouts and holes in which the meat is appropriately removed is also sufficient. .

FIG. 9 and FIG. 10 are mold A in the above first embodiment.
1 and B1, in the case of the second embodiment of the present invention (here, main molds A2 and B2 constituting the crankshaft mold are shown, and mold A2 has the second, fourth and sixth divided molds). The mold B2 constitutes each of the third and fifth divided molds.

In this case, the cavities of both molds A2B2 each have one space on the pitch circle in order to take six crankshafts.
When the cavities located at 20 degree intervals and adjacent to each other are rotated in a fixed direction around the mold center O, for example, 120 degrees clockwise, the phase will be 120 degrees clockwise around the crank journal part. A pair of three pieces formed in a relationship that is shifted from each other is made into a set, and then the two pieces are formed in a positional relationship that is 180 degrees out of phase with respect to the mold center 01, for example, on t different pitch circles as in the first embodiment. A total of six groups were formed.

The rest of the structure is the same as that of the first embodiment (the same parts are given the same reference numerals), and the same functions and effects can be achieved.

Further, FIGS. 11 and 12 show molds A3 and B3 in the case of the third embodiment of the present invention, and similarly, mold A3 is the second mold. The mold B constitutes the fourth and sixth divided molds, and the mold B constitutes the third and fifth divided molds.

In this case, the cavities of both molds A3 and B3 are formed in sets of three in the same manner as in the first embodiment, and are arranged in a positional relationship that is, for example, 180 degrees out of phase with respect to the mold center O on the same pitch circle. If you look at it differently, the cavities are located at 60 degree intervals on the pitch circle, and the phases of the adjacent cavities are in a constant direction around the mold center O, for example clockwise. 12 clockwise around the crank journal when rotated 60 degrees
Six pieces were formed, each offset by 0 degrees.

The other configurations are the same as those of the first embodiment, and the same effects are achieved.

Further, FIGS. 13 and 14 show molds A4 and B4 in the case of the fourth embodiment of the present invention, and molds A1 and B4 in the case of the first embodiment. B1 and mold A3 of the third example. In correspondence with mold A4.B3. The cavities of B4 are formed by two sets of three cavities formed in the same manner as in the second embodiment above, on the same pitch circle with a phase shift of 180 degrees with respect to the mold center O, for example. Yes, that is,
The cavities are located at 60 degree intervals on the pitch circle, and when the phases of adjacent cavities are rotated in a fixed direction around the mold center O, for example, 60 degrees clockwise, the phases are reversed around the crank journal part. Six pieces are formed so as to be offset by 120 degrees clockwise.

As explained above, according to the present invention, a plurality of molds divided into laminated molds in the axial direction are used to add six crankshafts for a three-cylinder engine in which the crank pin portions are out of phase by 120 degrees. The cavities of each part mold are spaced apart by 120 degrees on the pitch circle, and when the phases of adjacent cavities are rotated 120 degrees in a fixed direction around the center of the mold, the crankshaft is reached. Two sets of three molds are formed, one set being 120 degrees offset from the other around the journal part, and the above-mentioned plurality of molds have half the wall thickness and the same thickness at the crank pin part and both sides. Cavity a of the phase crank arm part
three molds A with a crank journal part and two molds B with a crank arm part cavity b half the wall thickness and 120 degrees out of phase on both sides of the crank journal part, and a crank journal part on the shaft end side. and the adjacent half-thick crank arm cavity C or d
The above-mentioned molds A and B are stacked alternately, and the above-mentioned molds C and D are placed on both sides to assemble the molds, and the molds are poured into the cavities of the assembled molds. Since six crankshafts are cast by this method, the bottom mold of the mold for the crankshaft for a three-cylinder engine can be made easily, and the stacking assembly of each mold and its casting can be easily performed. In addition, crankshafts for three-cylinder engines can be manufactured efficiently, and productivity can therefore be significantly improved.

In addition, if the molds C and D are common and have cavities of the same shape, there is an advantage that the molds can be assembled more easily, and the assembled mold can be divided into two. If you pour the metal into the outer mold of
If the crankshaft is vertically cast by providing a sprue in the center of -D, there is an advantage that the crankshaft can be cast more easily.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention, and FIGS. 1 to 8 show a first embodiment. FIG. 1 is a sectional view of a crankshaft mold for a three-cylinder engine, and FIG. The front and back views of the first mold, Figure 3 A and the opening are the front and back views of the second mold, Figure 4 A and the opening are the 3rd mold.
The front and back views of the mold, Figure 5 A and the mouth are the front and back views of the fourth mold, Figure 6 A and the mouth are the front and back views of the fifth mold, and Figure 7 A and the mouth are the front and back views of the mold. 6. The front and back views of the mold 6, Figure 8 A and 8 are the front and back views of the 7 mold, and Figures 9 and 10 are views corresponding to Figures 3 and 4, respectively, showing the second embodiment. , FIGS. 11 and 12 are views equivalent to FIGS. 3 and 4, respectively, showing the third embodiment, and FIGS. 13 and 14 are views equivalent to FIGS. 3 and 4, respectively, showing the fourth embodiment. be. 1...Crankshaft for 3-cylinder engine, 2
...Crank journal part, 3...Crank pin part, 4...Crank arm part, 11
~17...First to seventh molds, O...Mold center, A1. A2. A3A4 ・B1 ・B2.
B3. B4 ・C1・Dl °°°°°. Mold, axd...cavity, el...
...Convex dowel, C2...Concave dowel, L...
Diameter line.

Claims (1)

[Claims] 1. For obtaining six crankshafts for a three-cylinder engine in which the phases of the crank pin portions are shifted by 120 degrees,
A plurality of molds divided in the axial direction so that they can be stacked is prepared, and the cavities of each mold are located at intervals of 120 degrees on the pitch soil, and the phases of adjacent cavities are in a constant direction around the center of the mold. Two sets of three molds are formed in such a manner that they are shifted by 120 degrees around the crank journal when the paper rotates 120 degrees, and the plurality of molds are arranged around the crank pin. and three molds A with crank arm cavities a half the wall thickness and in the same phase on both sides, and a crank journal part and a crank arm part with half the wall thickness and 120 degrees out of phase on both sides thereof. Consisting of two molds B with cavities b, and one mold C and D each with cavities C or d in the crank journal part on the shaft end side and the half-thick crank arm part adjacent thereto. , the above-mentioned molds A and B are stacked alternately, and the above-mentioned molds C and D are arranged on both sides, and assembled,
A method for manufacturing a crankshaft for a three-cylinder engine, characterized in that six crankshaft castings are cast by pouring metal into the cavity of the assembly mold. 2. The method for manufacturing a crankshaft for a three-cylinder engine according to claim 1, wherein the molds C and D are common molds having cavities of the same shape. 3. The method for manufacturing a crankshaft for a three-cylinder engine according to claim 1 or 2, wherein the assembled mold is placed in a two-part outer mold and poured. 4. The method for manufacturing a crankshaft for a three-cylinder engine according to claim 1, 2, or 3, wherein the molds A to D have a sprue in the center and a crankshaft.