JPH02129305A - Manufacture of connecting rod - Google Patents

Abstract

PURPOSE:To manufacture a lightened connecting rod without needing cutting work by manufacturing one pair of divided bodies for the connecting rod vertically bi-secting through groove part with metal powder for sintering and brazing both divided bodies and integrating. CONSTITUTION:At the time of laying the connecting rod 11 so that an axial line A of a crankshaft hole 12 formed in a big-end part 11a comes to vertical, cross section of a column part 11c shows almost H-shape with a groove L extending to longitudinal direction of both side faces. One pair of the divided bodies 14, 15 having shapes dividing the connecting rod into two pieces with vertical plane to the axial line A passing the groove L in this connecting rod 11, are compacted with the metal powder for sintering and sintered, and brazing is executed under mutually facing condition to the divided surfaces 14e, 15e, and both bodies are integrated. By this method, the cutting work after sintering can be dispensed with and the connecting rod 11 lightened to the limit suiting the required values of strength and rigidity is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a connecting rod for engine parts, and a method for manufacturing a connecting rod having an H-shaped column section. Conventionally, the sintered connecting rod 1 described in Japanese Patent Application Laid-Open No. 62288713 has been manufactured mainly by hot forging method or sintering forging method, as shown in FIG. Crankshaft hole 2 formed in end 1a
in a state where the axis 11A of is placed vertically,
The column portion 1b has a cross section of one shape with recesses 3, 3 formed on both upper and lower surfaces thereof, respectively. In this way, connecting rods manufactured by forging are made to be easily formed by forging.
It was common to have a cross-sectional shape such as a shape.

In addition, connecting rods are required to have strength and rigidity as well as being lightweight in order to transmit the combustion pressure of the engine to the crankshaft. Reducing the weight of this connecting rod has become an important issue from the viewpoint of reducing lJ, noise, and friction. Therefore, as shown in FIG. 5, recesses 5, 5 each having an opening-shaped cross section are formed on both sides of the large end 4a, and the recesses 5 are extended in the longitudinal direction to form the column part 4.
An H-shaped cross-section connecting rod 4 has been developed in which weight reduction is achieved by making b into an H-shaped cross-section.

Problem to be Solved by Komei However, in the conventional hot forging method or sintering forging method, the H-shaped connecting rod 4 has a concave portion 5°5 which is an undercut on both sides of the column portion 4b. Due to structural constraints, it cannot be processed by forging alone, so in the past, first, the shape of the other parts was formed by forging, leaving only the recessed part 5. It is being processed.

The cutting process of the recesses 5, 5 of the H-shaped cross-section connecting rod 4 is as follows:
For example, as shown in Figure 6, machining is performed using a side cutter 6, which results in low productivity and high manufacturing costs. Currently, its uses are limited.

Further, the H-shaped connecting rod 4 is insufficient in terms of reducing the weight of the connecting rod, and there is still room for weight reduction. That is, the recesses 5, 5 of the H-shaped cross-section connecting rod 4 are formed in an R shape at a portion continuous with the large salt portion 4a and the small end portion 4C at both ends of the column portion 4b.
The radius of curvature R+ of the continuous part on the side and the radius of curvature R2 of the continuous part on the small end 4b side are both the same as the radius of curvature R2 of the continuous part on the side cuffer 6.
It is restricted by the size of the diameter. That is, assuming that the deepest part of the recess 5 has a depth h and the rotation shaft 6C on which the blade 68 of the side cutter 6 is attached has a radius r, the blade is The radius of the groove 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 rotation vJ axis (see FIG. 7). therefore,
The radius of curvature R+, R2 of the R-shaped portion cut using the blade 6a is the radius (h+r) of the blade 6a.
Since it is impossible to process to a smaller diameter, the radius of curvature R1, R2>h+r, and the radius of curvature R, R2 is the blade 6 of the side cutter 6.
As a result determined by the radius of a, the R-shaped portion of the concave portions 5, 5 of the H-shaped cross-section connecting rod 4 is cut to its rigidity or strength limit (cut to the point shown by the broken line in Fig. 6). It has been impossible to reduce the weight to the utmost with conventional manufacturing methods.

Furthermore, as mentioned above, the dimensions of the radius of curvature R+ and R2 are
In order to reduce the size of the H-shaped cross-section connecting rod 4 by making it as small as possible within the restricted range, the radius (h+r) of the blade 6a of the side cutter 6 is made as small as possible. The lifespan of the blade 6a is shortened and the blade 68 needs to be replaced frequently, which also increases manufacturing costs.

This invention was made against the above-mentioned technical background.
The object of the present invention is to provide a method for manufacturing a connecting rod with an H-shaped cross section that can reduce the weight to the limit of design.

Means for Solving the Problems As a means for solving the above-mentioned problems, the present invention provides a longitudinal direction on both sides when the connecting rod is placed so that the axis of the crankshaft hole formed in the large end thereof is perpendicular. In the method for manufacturing a connecting rod in which the column portion has a substantially H-shaped cross section by forming grooves extending in the column, the connecting rod is passed through the bottom of the grooves formed on both sides of the connecting rod and approximately aligned with the axis of the crankshaft 11 foot hole. After forming a pair of divided bodies in the shape of two halves on a perpendicular plane using sintering metal powder, these divided bodies are sintered, and during or after sintering, the dividing surfaces of both divided bodies are They are characterized by being integrated by brazing them in abutting contact with each other.

Function By adopting the above manufacturing method, a connecting rod with an H-shaped column section is divided into two parts, which are approximately perpendicular to the axis of the crankshaft hole formed in the large end of the connecting rod. The divided bodies are powder-molded, sintered, and integrated by brazing with the divided surfaces abutting each other, so there is no undercut shape in each divided body to be powder-molded. The weight can be reduced to the limit design in terms of strength and rigidity, and cutting machines and other machines are not required. Furthermore, the mold for molding the powder molded body becomes simple, and the occurrence of breakage and defective products when demolding the divided body due to powder molding is reduced.

EXAMPLE Hereinafter, an example of the method for manufacturing a connecting rod of the present invention will be described with reference to FIGS. 1 to 3.

When the connecting rod 11 is placed so that the axis A of the crankshaft hole 12 formed in the large end 11a (the right end in FIG. 3) is perpendicular (the state shown in FIG. 3), the connecting rod 11 has a cross section on both sides thereof. A mouth-shaped recess 13.13 is formed to extend in the longitudinal direction, and has a small end 11b opposite to the large end 11a.
The cross-sectional shape of the column part 11c in the direction perpendicular to the longitudinal direction is H-shaped, and the large end 11a side and the small end of each recess 13 extending in the longitudinal direction The concave portions 13 .
13, the weight of the connecting rod 11 is reduced by removing the thickness of the column portion 11c within a range where the design strength and rigidity are ensured.

The connecting rod 11 formed in such a shape is manufactured by compression molding metal powder or alloy powder into a predetermined shape and firing the molded powder compact. will be explained in detail.

The weight of the connecting rod 11 whose column part is H-shaped in cross section is reduced almost to the maximum by forming a concave part 13 by stealing the flesh on both sides of the column part 11c to the extent possible to satisfy the required values of strength and rigidity. Manufactured based on the designed limit design.

In addition, the material used is 4100 series low alloy steel powder (
Fe −0,77tJn −0,97Or −0,23
M0), graph of 0°6 weight%? and 0.5
A mixture of tJnS (wt%) and 0.8 wt% zinc stearate as a lubricant was used.

To mold the powder compact, first, the crankshaft hole 1 formed in the large end 11a of the connecting rod 11 shown in FIG.
2nd axis! ! ; Compression molding is performed using a molding die at an average surface pressure of 6 tons into a shape divided into upper and lower halves on a plane of symmetry perpendicular to AA. In this case, since the connecting rod 11 is divided into two along the plane of symmetry, both divided bodies can be molded using one molding die.

At this time, the pair of divided bodies 14.15 obtained by cutting the connecting rod 11 by 2fl have a through hole that will become a crankshaft hole, respectively, as shown in FIG.
5a (right end in FIG. 1), small end portions 14b and 15b which are the opposite ends thereof, and column portions 14c and 1 located between these.
It consists of 5c.

Further, on both sides of the column part 14c of one of the divided bodies 14,
L-grooves 14d (one not shown) each having an L-shaped cross section are formed on the dividing surface 14e (lower surface in FIG. 1),
On both sides of the column portion 15c of the other divided body 15, grooves 15d (one not shown) each having a cross-section are formed on the dividing surface 15e (upper surface in FIG. 1) side.
When the dividing surfaces 14e and 15e of the dividing body 14 and the dividing body 15 are brought into contact with each other, the facing grooves 14d and grooves 15
d forms the shape of a mouth-shaped recess 13. Therefore, the pair of divided bodies 14 and 15 do not have any shaped parts such as undercuts that make it difficult to remove the mold from the mold, so the shape and configuration of the mold can be simplified. At the same time, the incidence of molding defects such as cracks and breakage of the powder compact during demolding can be suppressed to a low level. This sintering is carried out in a N2 atmosphere with a dew point of -30'C or less after preheating and decomposing and evaporating the IIJ quencher.
It was baked at 1300°C for 60 minutes.

Next, a pair of divided bodies 14.1 sintered as described above
5, the respective dividing surfaces 14e and 15e are abutted against each other, and both dividing surfaces 14e.

Between 15e and 15e, commercially available sintering brazing material (Cu4ONi-
151Jn-2Si-18) and 15% [e powder] were sandwiched together and heated in a heating furnace for 11 hours.
Both divided bodies 14 and 15 were brazed at 30°C.

After that, brazing was performed in an atmosphere of 850°C for 30 minutes and then in an atmosphere of 400°C for 60 minutes ii! ! ] quality and further shot peening treatment (arc height 0.
2 to 0.3 rm, j'J haL/-91001 or more) eA connecting rod 11 having an H-shaped cross section (see FIGS. 2 and 3) was manufactured. In addition, in FIG. 2 and FIG. 3, the reference numerals indicate the abutment lines that appear at the boundaries of the divided bodies 14 and 15 that are sintered and brazed together.

When the connecting rod 11 manufactured in this way was weighed, it was found that it was approximately 10% lighter than a connecting rod manufactured by conventional hot forging with the same specifications.

In addition, when this connecting rod 11 was subjected to tension and compression tests using a hydraulic fatigue tester, the durability limit was σω-21K.
g/IRIA, and strength equivalent to that of conventional hot forged connecting rods was obtained.

In addition, in this embodiment, after separately sintering a pair of powder-molded divided bodies 14.15, both divided bodies 14.15
However, it is also possible to select the brazing material and sintering temperature appropriately and simultaneously braze and integrate the divided bodies 14 and 15 when sintering the divided bodies 14 and 15. In some cases, since brazing can be performed simultaneously with sintering, the process can be shortened.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the method for manufacturing a sintered connecting rod of the present invention is to produce a connecting rod with a column portion that is H-shaped in cross section, passing through the bottom of the groove formed on both sides of the connecting rod, and substantially perpendicular to the axis of the crankshaft hole. After powder-molding a pair of divided bodies with a shape divided into two along a plane, these divided bodies are sintered, and during or after sintering, the divided faces of both divided bodies are soldered so that they abut each other. Since the connecting rod is manufactured by attaching and fixing them together, by powder molding the parts into a pair, there is no undercut shape, and there is no need for cutting after sintering, which improves the strength and rigidity of the connecting rod. It is possible to carry out a limit design that reduces weight to almost the maximum within the range that meets the required value of.

In addition, the molding mold can be simplified, demolding is easy, the incidence of molding defects in powder compacts can be significantly reduced, and cutting work after sintering is no longer required, so conventional hot Compared to H-shaped connecting rods that are manufactured by forging and cutting with a cutter, they are lighter and can be manufactured at the same or lower cost, reducing costs to a level that can be applied to mass-produced engines. Has a point.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the method of the present invention, in which Figure 1 is a front view showing a pair of divided bodies formed by powder molding, and Figure 2 is a front view showing a pair of divided bodies formed by sintering. , a front view of a connecting rod integrated by brazing, FIG. 3 is a partial cross-sectional perspective view of the completed connecting rod, FIGS. 4 to 7 show conventional examples, and FIG. 4 shows a conventional general connecting rod. 〉 - A partial cross-sectional perspective view of a Rondo, Figure 5 is a partial cross-sectional perspective view of a conventional H-shaped connecting rod, Figure 6 is an explanatory diagram of a conventional H-shaped connecting rod processing method, and Figure 7 is a partial cross-sectional perspective view of a conventional H-shaped connecting rod. It is a sectional view taken along the line ■-■ in the figure. 11...Sintered connecting rod, 11a...Big end, 1
1b...small end portion, 11c...column portion, 12.
... Crankshaft hole, 13 ... Recess, 14,
15...min m1 body, 14d, 15d-L groove,
14e. 15e...dividing surface, A...axis of crankshaft hole.

Claims (1)

[Claims] When the connecting rod is placed so that the axis of the crankshaft hole formed in the large end is perpendicular, grooves extending in the longitudinal direction are formed on both sides, so that the column part has a cross section of approximately H.
In the method for manufacturing a connecting rod having a shape, the connecting rod is passed through the bottom of a groove formed on both sides of the connecting rod and divided into two by a plane substantially perpendicular to the axis of the crankshaft hole. After powder compacting with metal powder, these divided bodies are sintered, and during or after sintering, the divided surfaces of both divided bodies are brazed to be in contact with each other and integrated. A method for manufacturing connecting rods.