JPH0261342B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to forging and forming a connecting rod for an internal combustion engine, and more specifically, it eliminates burrs caused by forging and improves the shape factor and metal flow connection state. related to reducing the weight of the code.

A large inertial force acts on the connecting rod of an internal combustion engine due to the mass of the piston, piston pin, and the connecting rod itself. Reducing these inertial masses greatly contributes to improving engine responsiveness, output, and fuel efficiency.

However, in conventional forged steel or aluminum connecting rods, relatively large deburring marks 6 are left in the cracks of the forging die, as shown in Figure 1, resulting in a large shape factor. Since fatigue is more likely to be accelerated and the variation in fatigue strength is also large, causing the life of the rod part 1 to be inconsistent, the purpose of this method is to sacrifice the inertial mass of the connecting rod and prevent premature failure due to fatigue. The overall thickness has been increased to increase strength.

Therefore, the purpose of the present invention is to reduce the weight of connecting rods for internal combustion engines by controlling the occurrence of forging burrs, improving the metal flow connection state and shape factor, stabilizing fatigue strength, and reducing excess thickness. The purpose is to provide a manufacturing method that makes it possible.

The present invention will be described below with reference to drawings of embodiments.
2 to 4 show the forming process of the connecting rod in terms of the shape of the material. FIG. 2 shows the rod-shaped material 10, and FIG. A double-headed material 10c having spherical heads 11c and 12c at both ends of the shaft portion 13, respectively.
, and FIG. 4 shows a small end portion 12 formed by forming a double-headed material 10c in a closed forging die, thereby forming a small end hole 27 at one end into which a piston pin is to be fitted.
d, a large end portion 11d in which a large end hole 26 to be fitted with the crankshaft is formed at the other end, and a rod portion 13d connecting these parts, and the mold break line trace 2
3 shows a connecting rod 10d with almost no protruding forging burrs.

Connecting rod 10d shown in FIG.
The rod portion 13d is the fifth section representing the - cross section.
As is clear from the figure, the rod main portion 15d has an H-shaped cross section with ribs 16 and 17 formed on both sides. In addition, this connecting rod 10d is
The small end 12d and the large end 11d have a pair of small diameter recesses 25 and a pair of large diameter recesses 24 facing each other in the axial direction of the ends, and the recesses 24,
The holes 25 are later subjected to an appropriate cutting process and communicated with each other to form the small end hole 27 and the large end hole 26 described above.

Next, the forming of the double-headed material 10c and the connecting rod 10d will be explained in FIGS. 6 to 11.
This will be explained in detail using figures.

First, as shown in FIG. 6, a rod-shaped material 1 with a predetermined diameter and a predetermined length is prepared according to a pre-calculated material volume.
Prepare 0. Furthermore, in order to reliably prevent the occurrence of burrs during closed forging, an experimental result has been obtained that it is desirable that the variation in the material volume for the finished mold cavity be within ±1 g. This is based on the test results when providing a relief part for excess material due to variations, but it does not necessarily have to be within this range.

The prepared rod-shaped material 10 is inserted into the die-cutting hole 31 of the mold 30 as shown in FIG.
a. A rod-shaped material 10a having a large-diameter shaft portion 11a at the other end and a tapered intermediate shaft portion 13a therebetween and provided with a preliminary uneven thickness is formed.

Subsequently, the rod-shaped material 10a obtained by this molding
The divided molds 40 are matched as shown in FIG.
41 into the die-cutting hole 42 and upsetting it with punches 43 and 44 that move forward and backward in opposition.
A double-headed material 10c having shapes c and 12c formed thereon is molded. The double-headed material 10c is taken out from the mold by dividing the split molds 40 and 41.

In addition, in the forming process of FIG. 8, flat surfaces 111, 112, 1 are formed on the spherical heads 110c, 120c as shown in FIG. 9 in order to improve the stability of the material in the subsequent process.
21 and 122 may be molded simultaneously with the spherical head to form the double-headed material 10c. Further, the forming process of the double-headed material 10c is not limited to the above embodiment, but may be performed by combining the processes shown in FIGS. 7 and 8 into one process, or by rolling, roll forging, or the like.

However, when forming the double-headed material 10c, regardless of the method used, the uneven thickness is set as shown in Fig. 10 and 1 when the double-headed material 10c is formed into a connecting rod.
The volume of each part of the molding cavity of the closed forging die shown in Fig. 1, the spherical heads 11c, 12c, and the intermediate shaft part 13
The volume is determined to be approximately equal to the volume of c. That is, the small end 12 of the connecting rod 10d
d, the volumes of the small diameter spherical head 12c and the large diameter spherical head 11c are adapted to the large end 11d, and the rod part 1
The uneven thickness is set so that the volume of the tapered intermediate shaft portion 13c is adapted to 3d.

Next, double-headed material 1 formed with uneven thickness in this way
0c is supplied to a predetermined position within the die engraving 64 of the lower mold of the closed forging die, as shown in FIG. 10, in order to form it into a connecting rod shape.

Due to the operation of a press ram (not shown), the punch 53 and the mandrels 51 and 52 attached and fixed to the punch are lowered together with the pressure receiving plate 59, and the upper mold 50 suspended from the punch by tension bolts 55 and 56 is also integrated. and descends. The punch 53 and the upper mold 50 are fitted into a guide post 65 fixed to the lower mold 60, and the die-carved portion 64 of the lower mold 60
It is now possible to advance and retreat without any deviation.

When the punch 53 and the upper mold 50 further descend,
The upper die 50 and the lower die 60 are in close contact with each other, and the die-cut portions 54,
64 to form a closed molding space, and
The springs 57 and 58 are compressed, and the punch 54 and mandrels 51 and 5 are inserted into the die engraving part 54 of the upper die 50.
2 tips protrude.

As a result, the double-headed material 10c is sealed and forged into a desired shape as shown in FIG. A connecting rod 10d is formed, comprising a rod portion 13d having an H-shaped cross section and a rod portion 13d having holes 16 and 17 formed thereon.

Furthermore, as shown in FIG. 11, at the position where the mold sealing is completed and the punch has reached the predetermined bottom dead center, the closed forging mold has a small end portion 67, 68 for releasing surplus material due to variations in the material volume. 12d
The die-cut portion 54 is provided in an annular shape between the end faces of the large end portion 11d and the upper die-cut portion 54 which face each other in the axial direction of the mandrels 51 and 52 and is extended in the axial direction of the mandrels.

Note that even when providing relief parts for surplus material at locations other than the above two locations, the connecting rod die cut end face in the axial direction of the small end hole 27 and large end hole 26 formed in the small end 12d and large end 11d. It is best to form it by engraving an extension.

By providing such surplus material relief parts 67 and 68, surplus material due to variations in the material volume is absorbed by the small end 12d and the large end 11d in the form of small variations in the axial dimension thereof, At the same time, the forging stress acting on the closed mold is relaxed, making it difficult for mold breakage to occur, resulting in a stable mold life.

The molded connecting rod 10d is removed from the closed mold by raising the upper mold 50 and punch 53 in the same manner as shown in FIG. 10, and by raising the knockout bar 60. As shown in FIGS. 4 and 5, the connecting rod 10d molded in this manner has almost no burrs on the mold break line 23, and no burr removal step is required.

Thereafter, the connecting rod 10d is completed by performing predetermined processing.

If further weight reduction is desired, the connecting rod 1 obtained by closed forging may be used.
As shown in Fig. 14, make a hole 2 in the rod part 13d of 0d.
4,25 can also be formed.

To briefly explain the punching process, first, as shown in Fig. 12, a connecting rod 10d is
is installed on the lower mold 80 and the lower mold holder 81
A small diameter protrusion 86, a small diameter recess 25 in the large diameter protrusion 87,
The large diameter recess 24 is fitted and positioned, and then the upper mold 70 and punches 72, 73 are lowered to lower the lower mold 8.
Holes 24 and 25 are punched out in the rod portion 13e using the No. 0 blades 82 and 83 and the punches 72 and 73, as shown in FIG.

As described above, according to the present invention, since the occurrence of forging burrs can be prevented, the shape factor and metal flow connection state of the forged connecting rod can be improved, and the fatigue strength can be stabilized and the strength can be improved. As a result, it is possible to reduce the size of the shape factor due to deburring marks and the excess thickness that was provided to compensate for poor metal flow connections, thereby reducing the weight of the connecting rod. have

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view of the main part of a connecting rod with deburring marks formed by a conventional manufacturing method. FIGS. 2 to 4 are explanatory diagrams representing embodiments of the present invention and showing the process of forming a connecting rod using the shape of a material. Figure 5 is the − of Figure 4.
FIG. 3 is a cross-sectional explanatory diagram of main parts showing a cross section. Figures 6 to 1
FIG. 1 is an explanatory diagram of the manufacturing process corresponding to FIGS. 2 to 4. FIGS. 12 to 14 are explanatory diagrams of the process of forming a hole in the rod portion of the connecting rod shown in FIG. 4 and the punched hole product. Explanation of symbols, 10...rod-shaped material, 10c...double-headed material, 10d...connecting rod, 1
1c, 12c... spherical head, 11d... big end,
12d...small end, 13d...rod, 50...upper die, 53...punch, 60...lower die, 54...die engraving part, 67, 68...relief part, 26...large end Hole, 27...Small end hole, 23...Mold split line trace.

Claims (1)

[Claims] 1 Small end hole 27 to be fitted with a piston pin at one end
a small end 12d having a small end 12d, and a large end 11d having a large end hole 26 to be fitted with a crankshaft at the other end
In the method for manufacturing a connecting rod 10d for an internal combustion engine, which includes a rod portion 13d connecting these rods, in the first step, a rod-shaped material 10 is given a desired uneven thickness, and a spherical shape is formed at both ends of the rod-shaped material 10. The double-headed material 10c having the heads 11c and 12c formed thereon is molded, and in a second step, the double-headed material 10c is made into the small end hole 27 and the large end hole 26 to release the excess material 67, 68 due to the variation in the material volume. The closed forging molds 50, 53, 60 are extended and carved on the end face of the connecting rod die carved part 54 in the axial direction.
Ribs 16 are provided on both sides of the rod main portion 15d, which connects the small end portion 12d and the large end portion 11d at both ends.
17. A method for manufacturing a connecting rod for an internal combustion engine, which comprises sealingly forging a desired connecting rod 10d comprising a rod portion 13d having an H-shaped cross section and a rod portion 13d having an H-shaped cross section.