JPH0641604B2 - Connecting rod manufacturing method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a connecting rod for an engine component, particularly a connecting rod having a column-shaped H-shaped cross section.

2. Description of the Related Art Conventionally, connecting rods (hereinafter referred to as connecting rods) have been conventionally manufactured mainly by a hot forging method or a sintering forging method. For example, the sintering described in JP-A-62-288713. As shown in FIG. 4, the connecting rod 1 is placed so that the axis A of the crankshaft hole 2 formed in the large end 1a of the connecting rod 1 is vertical,
The column portion 1b has an I-shaped cross section in which concave portions 3 are formed on both upper and lower surfaces. In this way, the connecting rod manufactured by forging should be easy to form by forging.
Generally, the cross-sectional shape such as a shape was used.

In addition, the connecting rod is a component that is required to have strength and rigidity in order to transmit the combustion pressure of the engine to the crankshaft and to be lightweight, and in recent years, particularly from the viewpoint of reducing engine vibration and noise, reducing friction, etc. Therefore, weight reduction of this connecting rod has become an important issue. Therefore, as shown in FIG. 5, concave portions 5 and 5 each having a U-shaped cross section are formed on both side surfaces on the side of the large end portion 4a, and the concave portion 5 is extended in the longitudinal direction so that the column portion 4b has an H-shaped cross section. The H-shaped connecting rod 4 having a lighter weight has been developed.

However, in the H-shaped cross-section connecting rod 4, in the conventional hot forging method or sintering forging method, the recesses 5 and 5 which are undercuts on both side surfaces of the column portion 4b are formed in the mold. Due to structural restrictions, it is not possible to process only by forging. Therefore, conventionally, the recesses 5 and 5 are first left to be processed to form the other parts by forging, and then the recesses 5 and 5 are machined. is doing.

The recesses 5 and 5 of the H-shaped connecting rod 4 are cut by
For example, as shown in FIG. 6, the machining is performed by the sand cutter 6, and therefore the productivity is low and the manufacturing cost is high. The current situation is that the application is limited.

Moreover, the H-shaped connecting rod 4 is insufficient in terms of weight reduction of the connecting rod, and there is still room for weight reduction. It is the recess 5, 5 of the H-shaped connecting rod 4.
Is a large end portion 4a and a small end portion 4c at both ends of the column portion 4b.
The R shape is formed in the part continuous with the large end 4
The radius of curvature R ₁ of the continuous portion on the a side and the radius of curvature R ₂ of the continuous portion on the small end 4b side are both the disk-shaped blade 6a of the side cutter 6.
Is constrained by the size of the diameter. That is, assuming that the deepest part of the recess 5 is the depth h and the rotary shaft 6c for mounting the blade 6a of the side cutter 6 is the radius r, the edge of the recess 5 and the rotary shaft 6b are prevented from interfering with each other, so The radius of 6a needs to be larger than the sum of the depth h of the deepest part of the recess 5 and the radius r of the rotating shaft (see FIG. 7). Therefore,
The radius of curvature R ₁ and R ₂ of the R-shaped portion that is cut using the blade 6a cannot be machined to have a smaller diameter than the radius (h + r) of the blade 6a. Therefore, the radius of curvature R ₁ , R ₂ > h + r, and the curve radii R ₁ and R ₂ are the blades 6 of the side cutter 6.
As a result of being determined by the radius of a, the R-shaped portions of the recesses 5 and 5 of the H-shaped connecting rod 4 are cut to the limit of rigidity or strength (by cutting to the place shown by the broken line in FIG. 6). It has been impossible to reduce the weight to the limit by the conventional manufacturing method.

Further, as described above, in order to reduce the weight of the H-shaped cross-section connecting rod 4 by making the dimensions of the curve radii R ₁ and R ₂ as small as possible within the restricted range, the radius (h + r) of the blade 6a of the side cutter 6 ), The life of the blade 6a of the side cutter 6 is shortened and the blade 6
Frequent replacement of a is also a cause of increasing the manufacturing cost.

This invention was made under the technical background described above,
It is an object of the present invention to provide a method of manufacturing a connecting rod having an H-shaped cross section, which enables weight reduction to the limit design.

Means for Solving the Problems As a means for solving the above problems, the present invention provides a longitudinal direction on both side surfaces when the crankshaft is formed so that the axis of a crankshaft hole formed at the large end of the connecting rod is vertical. In a method of manufacturing a connecting rod in which each column has a substantially H-shaped cross section, the connecting rod passing through the bottoms of the grooves formed on both sides of the connecting rod and being substantially perpendicular to the axis of the crankshaft hole. A pair of divided bodies each having a shape divided into two surfaces are powder-molded with a metal powder for sintering, and these divided bodies are sintered, and the divided surfaces of both divided bodies are separated from each other during or after the sintering. It is characterized by brazing in an abutted state and integrating.

Operation By adopting the above-mentioned manufacturing method, the column portion is a pair of divided rods each having a H-shaped cross section divided into two by a plane substantially perpendicular to the axis of the crankshaft hole formed at the large end of the connecting rod. The powder is molded into a body, and these are sintered and brazed into a state in which the divided surfaces are abutted against each other to be integrated. Also, the weight can be reduced to the limit design in terms of rigidity, and machining such as cutting is unnecessary. In addition, the mold for molding the powder compact is simplified, and the number of damages and the occurrence of defective products when the divided body is released from the powder compact is reduced.

EXAMPLE An example of a method for manufacturing a connecting rod according to the present invention will be described below with reference to FIGS. 1 to 3.

The connecting rod 11 is placed so that the axis A of the crankshaft hole 12 formed at the large end portion 11a (right end in FIG. 3) is vertical (state in FIG. 3), and the cross-sections are formed on both side surfaces thereof. The U-shaped recesses 13, 13 are formed so as to extend in the longitudinal direction, and the large end 11a and the small end 11 on the opposite end are formed.
The column portion 11c in the middle of b is formed to have an H-shaped cross-sectional shape in the direction perpendicular to the longitudinal direction, and the large end portion 11a side and the small end of each recess 13 extending in the longitudinal direction. On the side of the portion 11b, each of the concave portions 1 is formed so as to have an R shape with a predetermined radius and become gradually shallower.
3 and 13, the weight of the connecting rod 11 is reduced by stealing the meat of the column portion 11c within the range where the design strength and rigidity are secured.

The connecting rod 11 formed in such a shape is produced by compressing and molding a metal powder or an alloy powder into a predetermined shape and firing the formed powder compact. Will be specifically described.

The connecting rod 11 having an H-shaped cross section has a column portion 11c formed with a recess 13 by stealing the meat on both sides of the connecting rod 11 so that the required values of strength and rigidity can be satisfied. Manufacture based on the limit design.

The materials used were low alloy steel powder of 4100 series (Fe-0.77Mn-0.97Cr-0.23Mo), 0.6% by weight of graphite and 0.5% by weight of MnS, and 0. A powder mixed with 8% by weight of zinc stearate was used.

The powder compact is first molded by the crankshaft hole 1 formed in the large end portion 11a of the connecting rod 11 shown in FIG.
A symmetric surface perpendicular to the axis A of 2 is divided into upper and lower halves and compression-molded with a molding die at an average surface pressure of 6 tons. In this case, since the connecting rod 11 is divided into two parts by the plane of symmetry, both divided parts can be formed by one forming die.

At this time, the pair of divided bodies 1 obtained by dividing the connecting rod 11 into two
As shown in FIG. 1, reference numerals 4 and 15 denote large end portions 14a and 15 having through-holes serving as crankshaft holes.
a (the right end in FIG. 1) and the opposite small end 1
4b, 15b and the column portions 14c, 15 intermediate between them
It consists of c and. In addition, the column portion 14 of one of the divided bodies 14
On both sides of c, L-shaped grooves 14d (one of which is not shown) each having an L-shaped cross section are formed as split surfaces 14e (lower surface in FIG. 1).
L-shaped grooves 15d (one not shown) having L-shaped cross sections are formed on both sides of the column portion 15c of the other divided body 15 on the divided surface 15e (upper surface in FIG. 1) side. And each divided surface 14 of the divided body 14 and the divided body 15.
The above-mentioned L groove 1 facing each other when abutting e and 15e against each other
4d and the L groove 15d form a U-shaped concave portion 13. Therefore, the pair of divided bodies 14, 15
Since there is no shape part such as undercut that makes it difficult to remove from the molding die, the shape and configuration of the molding die can be simplified, and the powder compact at the time of demolding It is possible to suppress the occurrence rate of molding defects such as cracks and breakage of the resin to a low level. In this sintering, after preheating to decompose and evaporate the lubricant, the sintering was performed at 1300 ° C. for 60 minutes in an N ₂ atmosphere having a dew point of −30 ° C. or less.

Next, the pair of divided bodies 14, 1 sintered as described above
No. 5, the split surfaces 14e, 15e are made to abut against each other, and a commercially available brazing material for sintering (Cu-40Ni-15Mn-2Si-1B) and 15% Fe powder are provided between the split surfaces 14e, 15e. The brazing material mixed with and is sandwiched, and in that state, 1
Both split bodies 14 and 15 were brazed at 130 ° C.
Then, after brazing, tempering is performed in an atmosphere of 850 ° C. for 30 minutes and in an atmosphere of 400 ° C. for 60 minutes, and further shot peening treatment (arc height 0.2 to 0.3 m).
m, coverage 100% or more) to produce a connecting rod 11 having an H-shaped cross section (see FIGS. 2 and 3). In FIGS. 2 and 3, reference numeral L is an abutting line that appears at the boundary between the divided bodies 14 and 15 that are sintered and integrally brazed.

Then, when the connecting rod 11 manufactured in this way was weighed, about 10% weight reduction was achieved compared with the connecting rod manufactured by the conventional hot forging having the same specifications.

Further, when a tension / compression test was conducted on this connecting rod 11 using a hydraulic fatigue tester, the durability limit σω = 21 kg
/ mm ^2, which is equivalent to the strength of the conventional hot forged connecting rod.

Further, in this embodiment, after the pair of powder-molded divided bodies 14 and 15 are separately sintered, both divided bodies 14 and 15 are
However, the brazing material and the sintering temperature may be appropriately selected, and the divided bodies 14 and 15 may be brazed and integrated at the same time when the divided bodies 14 and 15 are sintered. In this case, the process can be shortened because the brazing can be performed simultaneously with the sintering.

EFFECTS OF THE INVENTION As described above, in the method for manufacturing a sintered connecting rod of the present invention, the column portion is a connecting rod having an H-shaped cross section that passes through the bottoms of the grooves formed on both side surfaces thereof and is substantially perpendicular to the axis of the crankshaft hole. After the powder molding of a pair of divided bodies having a shape divided into two parts, these divided bodies are sintered, and the divided surfaces of both divided bodies are abutted against each other during or after the sintering. Since it is attached and integrally manufactured, the undercut shape part is completely eliminated by dividing the powder into a pair of divided bodies and cutting work after sintering is unnecessary, so that the strength and rigidity of the connecting rod can be improved. It is possible to make a limit design that reduces the weight to the limit within the range that meets the required value.

In addition, the molding die can be simplified, the mold can be easily removed, the incidence of defective molding of the powder compact can be significantly reduced, and cutting work after sintering is unnecessary. Compared with the H-shaped connecting rod manufactured by forging and then cutting with a cutter, it is lighter in weight and can be manufactured at a cost equal to or less than that of the H-shaped connecting rod. Have a point.

[Brief description of drawings]

1 to 3 show one embodiment of the method of the present invention. FIG. 1 is a front view showing a pair of powder-molded divided bodies, and FIG. , A front view of a connecting rod integrated by brazing, FIG. 3 is a partial sectional perspective view of a completed connecting rod, FIGS. 4 to 7 show a conventional example, and FIG. 4 is a conventional general connecting rod. 5 is a partial sectional perspective view of a conventional H-shaped connecting rod, FIG. 6 is an explanatory view of a method for processing a conventional H-shaped connecting rod, and FIG. 7 is a VII of FIG. It is a VII line sectional view. 11 ... Sintered connecting rod, 11a ... Large end, 11b ... Small end, 11c ... Column, 12 ... Crankshaft hole, 1
3 ... Recesses, 14, 15 ... Divided bodies, 14d, 15d ... L
Grooves, 14e, 15e ... Dividing surface, A ... Axis of crankshaft hole.

Claims (1)

[Claims] 1. A column portion has a substantially cross-section by forming longitudinally extending grooves on both side surfaces when the crankshaft hole formed in the large end portion of the connecting rod is mounted so that the axis of the crankshaft is vertical. In a method of manufacturing an H-shaped connecting rod, a pair of divided bodies each having a shape obtained by dividing the connecting rod through a bottom of a groove formed on both side surfaces of the connecting rod and dividing the connecting rod in a plane substantially perpendicular to an axis of the crankshaft hole are sintered. Characteristic that after the powder molding with the metal powder for use, these divided bodies are sintered, and the divided surfaces of both divided bodies are brazed in abutment with each other during or after the sintering. And a method for manufacturing a connecting rod.