JP3468603B2 - Method for manufacturing sintered connecting rod - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a connecting rod of an internal combustion engine, a piston type compressor, a pump, etc. by powder metallurgy.

[0002]

2. Description of the Related Art A connecting rod of an internal combustion engine has a small end portion 6 having a piston pin hole 1b as shown in FIG.
And a large end portion 7 having a bearing hole 7a that fits into the crankshaft are connected by a rod portion 1a. Also,
Due to the convenience of assembly, the large end 7 side is the planned split surface (matching surface)
It is divided by 5 and comprises a main body portion 1 and a cap portion 2. The main body portion 1 and the cap portion 2 are integrally fixed by passing bolts through bolt holes (not shown). When used, the piston pin hole 1b and the crankshaft bearing hole 7a
A bearing member may be attached to the device for use.

When the main body 1 and the cap portion 2 of the connecting rod are manufactured by powder metallurgy, the main body portion 1 and the cap portion 2 are compacted and sintered into an integral shape, and if necessary, forged to improve the height. After the density is determined, the surface is divided at a planned dividing surface (a mating surface) 5 that passes through the center of the bearing hole 7a of the crankshaft. An example of this dividing method is, for example, Jitsuho Sho 57-47.
As disclosed in Japanese Patent Publication No. 453 and Japanese Patent Publication No. 26087/1990, a method in which a splitting auxiliary hole is provided in advance in a portion to be fractured and the material is to be fractured. In the notch groove, a method of cutting after breaking the remaining meat portion, a portion having a different hardness by carburizing and quenching is provided in the planned breaking portion, and a method of making the fracture surface uneven by breaking, Japanese Patent Laid-Open No. 1-272705
As described in Japanese Patent Laid-Open Publication No. 59-1077, a method of forming an oxide film in the groove and then breaking by forming a groove at a portion to be broken in the molded body and performing sintering and forging.
As described in Japanese Patent Publication No. 05-05, a sintered body having an integral shape is sheared and separated by shifting a main body portion and a cap portion with a punch in a mold.
Examples include a method of further compressing each part and forging.

[0004]

Compared with the conventional method of cutting a sintered body or forged body integrally molded and adjusting the dimension and shape by cutting, according to the above-mentioned conventional fracture splitting method, the fracture surface is It can be used as a mating surface as it is,
Since the mating surfaces have irregularities that mesh with each other, there is an advantage that the main body portion and the cap portion can be positioned.

On the other hand, a large breaking load is required for division, and deformation occurs in the case of a material having high ductility such as an aluminum alloy. Therefore, there are restrictions on the selection of the material. There is a problem such as room for improvement in positioning workability. In the method of shearing the sintered body in the mold and forging each, a large pressure is required for shearing, the forging device has a complicated structure, and the unevenness as described above is formed on the divided end faces. Therefore, there are problems such as poor positioning workability.

Further, in the conventional connecting rod manufacturing method, it is difficult to change the material of each part so as to meet the required characteristics of the main body and the cap portion or the required characteristics of the bearing portion. In view of the above situation, the present invention provides a sintered connecting rod that can be easily divided into a main body portion and a cap portion, and has good positioning workability during assembly and assembly and assembly dimensional accuracy, and a crankshaft bearing. The purpose of the invention is to provide a connecting rod in consideration of the functions of the parts.

[0007]

[Means for Solving the Problems] To achieve the above object,
According to the present invention, a main body portion and a cap portion of a connecting rod are compacted into an integrally molded body having a deviation from each other along a planned dividing surface to obtain a sintered body, and the sintered body is made in a direction in which the deviation is zero. A method for manufacturing a sintered connecting rod is provided, comprising compressing in a mold to apply shear to the planned dividing surface, and then applying pressure until the planned dividing surface comes into close contact with it to cause plastic deformation.

Further, one of the main part and the cap part of the connecting rod is formed by integrally mounting a large end bearing which is offset from each other along the planned dividing surface, and the other is formed at the large end. The bearing is excluded from the molding, and the main body and the cap are divided into two parts, and the divided surfaces of the sintered body are opposed to each other. Then, the planned dividing surfaces of the main body portion and the cap portion are opposed to each other, and the respective dividing planned surfaces and the outer peripheral surface of the bearing and the inner peripheral surface of the opposing member are pressed and plastically deformed. A method for manufacturing a sintered connecting rod is provided. In this case, the main body portion and the cap portion may be different alloys.

In these methods, in order to form a surplus due to plastic deformation in the shaft hole of the large end and to reduce the density of the cap portion of the connecting rod and the crankshaft bearing portion, the cap portion is formed more than the main portion. A sintered body having a low or low density, a main body sintered body and a cap sintered body made of different alloys, and a main body sintered body and a cap sintered body made of an aluminum alloy Can be

[0010]

[Function] When the integrally molded sintered bodies that are displaced from each other along the planned dividing surface are compressed from above and below in the direction in which the end surfaces of the planned dividing surface are aligned, the displaced parts are sheared in the vertical direction, and the main body part The cap portion is divided and the surfaces to be divided face each other. Compared with the case of shearing the entire thickness of the large end portion, this shearing is formed by shifting the sintered body along the planned dividing surface, so the shearing area is small and can be performed with a low pressing force. .

The sheared surface is a surface to be divided, and the surfaces face each other. When each member is further compressed, the member is plastically deformed and its density is increased to form the shape of a connecting rod, and the surfaces to be divided are brought into close contact with each other. The closely scheduled dividing surface is formed with waviness and wavy unevenness (wrinkles) due to plastic flow, and unevenness due to unevenness of the sheared surface.

Since this close contact has an appropriate joining strength, the members will not be split or move during the cutting process or the screw hole process. Therefore, it is convenient in terms of processing efficiency and processing accuracy. Further, since this close contact is brittle, the joining force is not so strong, so that it can be divided by applying an external force. After dividing once, when aligning and assembling again, it becomes possible to accurately and easily perform the alignment at the time of assembly due to the waviness and the unevenness.

If a surplus (web) is formed in the large-end shaft hole during the plastic working, the surplus part is made of a relatively strongly bonded material, which makes it difficult to divide the two members. It has an effect. The joining force of the members can be adjusted depending on the size of the extra thickness, and the removal can be facilitated by removing the members by cutting or the like. The same applies to the case where a sintered body in which a semicircular bearing is shifted along the planned dividing surface to form a large end bearing is used for either the main body portion or the cap portion. When a semicircular bearing is pressed and sheared against the part to make the divided end faces face each other, and then the whole is compressed from above and below for plastic flow, the opposite end faces come into contact with each other to be in a close contact state. Further, the outer peripheral surface of the semicircular bearing portion and the inner peripheral surface of the mating member are also plastically deformed to be in close contact with each other.

If a surplus wall is formed in the large-end shaft hole during this plastic deformation, the material of the bearing portion plastically flows toward the surplus wall portion, so that the opposing mating member is also surplus. The back surface of the meat undergoes plastic flow to increase the contact area, and the bearing portion and the mating member are more firmly bonded. Compared to the main part, if the height of the semicircular bearing that is sheared and adheres to the mating member is shortened or plastic working is performed using a low density sintered body, shearing will be easier and the adhesion will be better than that of the main part. The resulting swelling of the planned end surface is large, and a connecting rod with a low density of the cap and large end bearings can be obtained, and oil can be impregnated into the pores of the cap member and bearing, which helps lubrication during sliding. . In addition, the weight of the cap part is lightened to reduce inertia during operation.

According to this manufacturing method, the cap portion side is made of an alloy in which sliding characteristics are emphasized and the main body side is made of an alloy in which strength is emphasized. It is possible to combine different alloys, such as using an alloy with excellent characteristics and making the cap part a low-grade alloy, or making the cap part and the bearing porous and excellent in sliding properties. Individuality can be added to the characteristics of the connecting rod.

Further, since it can be divided with a force smaller than that of the conventional method, it is suitable for a product made of an aluminum alloy which is easily deformed by the conventional method and has excellent ductility.
Waviness and wavy irregularities (wrinkles) generated by plastic working become large, and positioning during assembly can be performed accurately and accurately and easily. In addition, oil on the planned dividing surface of the sintered body,
When a resin, mold release agent, graphite, or other coating film is provided and plastic working is performed, the bonding force is reduced, and division is facilitated. For plastic working, cold, warm, or hot is applied depending on the type of alloy, required density, and the like. In order to enhance the properties of the alloy, heat treatment or surface treatment is carried out as necessary in the same manner as in the past.

The main body portion and the cap portion are divided by bending at the planned dividing surface, press-fitting a taper pin into the shaft hole, mounting a half-cutting jig in the shaft hole, and expanding the jig with a wedge. It can be performed by a method or the like.

[0018]

【Example】

[First Embodiment] The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view for explaining a plastic working method for facilitating the understanding of the present invention. In the mold apparatus, the lower punch 21 is fitted to the die 10 and the upper first punch 3 is fitted to the upper ram 40.
The first and upper second punches 32 are provided. Upper first punch 3
1 can move back and forth via a hydraulic cylinder 41.
The sintered body 3 has a step-like shape with a step 9, as shown in FIG.
It is inserted into the die cavity as shown in (a). The sintered body 3 is divided from the planned dividing surface, and the dividing surfaces are generated so as to be displaced from each other, and the deviation is the step 9.

The step 9 is provided so as to coincide with the planned dividing surface of the sintered body 3. Then, as shown in FIG. 1B, the upper ram 40 is lowered and the upper punches 31 and 32 are attached to the sintered body 3.
When the upper ram 40 is further lowered after coming into contact with the upper ram 40, the piston of the hydraulic cylinder 41 rises to bring the upper first punch 31 into a state of holding the sintered body 3 and the upper second punch 32 to the sintered body 3. 3 is pressed down to shear from the step 9,
As shown in (c), the upper end surfaces of the sintered bodies 3 are aligned. When the upper ram 40 is further lowered, the sintered body 3 is compressed,
The outer surface is modeled by plastic deformation and the planned dividing surface 5 is closely joined. After that, as shown in FIG. 1D, the upper ram 40 and the lower punch 21 are lifted to release the plastically worked body from the mold.

FIG. 2 is a top view of the connecting rod, and FIG. 3 is a sectional view taken along the line AA of FIG. 2, showing the shape of the sintered body of the connecting rod. The planned dividing surface 5 of the large end portion 7 has a stepped shape with a step 9. This sintered body is obtained by compacting and sintering a mixed powder of an iron-based, aluminum-based alloy composition or the like. Depending on the type of alloy and the required properties of the connecting rod, the sintered body is kept at room temperature or is heated and compressed in a mold to be plastically worked.

4 and 5 are longitudinal sectional views showing the process of plastic working of the connecting rod of FIG. The mold is a die 10, a lower punch 21, a small-diameter core 11, and a large-diameter lower core 12.
b, a large-diameter upper core 12a having a projection 12d on its end surface, an upper first punch 31 and an upper second punch 32 which are divided by the center line of the large-diameter core and are in sliding contact with a dividing surface 33. The large core has a structure divided into upper and lower parts, but the small core 1
Similar to the structure of 1, one core is also possible.

As shown in FIG. 4, the sintered body 3 is set on the mold cavity, the lower punch 21 is lowered, and the upper punches 31 and 32 and the large-diameter upper core 12a are lowered, so that both upper punches are lowered. The punches 31 and 32 press the upper end surface of the sintered body 3, and the large-diameter upper core 12a enters the bearing hole 7a of the sintered body 3 and contacts the large-diameter lower core 12b. Ryokami punch 3
When the 1, 32 and the large-diameter upper core 12a are lowered, the lower punch 21 and the large-diameter lower core 12b follow and descend, and the sintered body 3 is inserted into the mold. Then, only the upper second punch 32 is lowered, and the cap portion 2 of the sintered body is guided and lowered by the die hole, the side surface of the upper first punch 31 and the large-diameter cores 12a and 12b. At this time, the sintered body 3 is sheared along the step 9, and the planned dividing surfaces of the main body portion 1 and the cap portion 2 face each other. Then, when the sintered body is compressed by the upper and lower punches 31, 32 and 21, the density of the sintered body 3 increases, the outer shape is shaped, plastically flows, and the sheared divided end surfaces come into close contact with each other, as shown in FIG. At the same time, a surplus thickness (web) 7b is formed in the gap 12c where the upper and lower large-diameter cores 12a and 12b face each other.
The release of the plastically worked body is performed by returning the mold to the state shown in FIG.

The planned dividing surface 5 of the connecting rod plastically worked body is in close contact with the corrugated uneven surface generated by the undulations and the plastic flow, and when a surplus portion is provided, the plastic flow in that portion is large and a strong adhesion state is obtained. Has become. When the surplus portion is attached, the force required for division is high, and when the surplus portion is removed, the force required for division is reduced. If you want to reduce the adhesive strength of the surface to be divided of the plastically worked body to facilitate the splitting, the plastic deformation amount is small, the excess thickness is small, and a mold release agent is applied to the step 9 surface of the sintered body to perform the plastic working. I do.

When the density of the cap portion 2 of the sintered body is formed lower than that of the main body portion 1, shearing is easy, and the unevenness of the sheared surface becomes relatively large, so that the positioning property when assembling the main body portion and the cap portion is improved. Can be better and also
The weight of the cap portion of the plastically worked body is reduced, and the inertia loss during use can be reduced. Even if the thickness of the cap portion 2 of the sintered body is smaller than that of the main body portion 1, substantially the same effect as described above can be obtained.

The main body 1 and the cap 2 are divided by fixing one and bending the other, or by inserting a taper pin into the bearing hole. The divided planned surface 5 has undulations and corrugations, and if the undulations and concavities and convexities are used when reassembling, positioning can be performed easily and accuracy can be matched. Bolt hole processing, bearing hole processing and the like are preferably performed on the plastically worked body, but it is also possible to divide and then align and fix with a jig or the like. The heat treatment, if necessary, is the same as the conventional one. [Embodiment 2] Next, FIGS. 6 and 7 show a semicircular bearing portion 8
It is a top view of the sintering connecting rod provided with. 1 is different from FIG. 1 in that the cap portion 2 and the bearing portion 8 are
In FIG. 7, the main body portion 1 and the bearing portion 8 are made of the same material.

With this structure, for example, in the case of FIG. 6, the main body 1 is made of a material with emphasis on strength, and the cap 2 is used.
The bearing portion 8 and the bearing portion 8 can be made of a material that emphasizes sliding characteristics. In FIG. 7, the main body portion 1 and the bearing portion 8 are made of a material having good strength and slidability, and the cap portion 2 is made of a low-grade material. Therefore, the characteristics of the connecting rod can be improved.

The manufacturing method will be described below by taking the case of the structure shown in FIG. 6 as an example. FIG. 8: is AA of the sintered compact shown in FIG.
A sectional view and FIG. 9 are perspective views of FIG. The appearance of the main body 1 is the same as that of the example 1, and the material with emphasis on strength is selected. The cap portion 2 has a semicircular bearing portion 8 on the planned dividing surface 5.
It has an uneven shape and is molded by powder molding. A material with low density is selected with an emphasis on sliding wear resistance.

For example, the sintered alloy of the cap portion 2 is an aluminum sintered alloy proposed in Japanese Patent Application No. 6-37606, and the composition is basically an Al--Si--Cu--Mg type alloy. Exhibits a mottled structure of an Al-Si alloy phase containing a predetermined amount of Si in a dispersed state and a relatively soft Al solid solution phase, and the area ratio of the mottled tissue is 20 to 8
At 0:80 to 20, the maximum grain size of primary Si in the Al-Si alloy phase is specified to be 5 to 60 μm, so that it has both strength and wear resistance, and further contains a predetermined amount of transition metal. As a result, the Cu alloy phase at the grain boundaries is reduced, and the ductility is also improved. The manufacturing method of this alloy is Al-20% Si
Cu-4% Ni alloy powder and Al-50% Mg alloy powder are mixed with a powder obtained by mixing alloy powder and pure Al powder at a ratio of 60:40, and the total composition is Si12%, Cu3%, M.
g 0.5%, Ni 0.13%, balance Al, and this mixed powder is compacted and sintered.

The sintered alloy of the main body 1 is similar to, for example, the above-mentioned sintered alloy, except that the sintering conditions are changed so that the maximum grain size of the primary crystal Si in the Al--Si alloy phase is changed. The tensile strength after solutionizing and aging treatment is about 420 MPa, which is higher than the tensile strength of about 370 MPa of the sintered alloy of the cap portion. When such a sintered body is pressed against the semi-circular end surface of the bearing portion 8 in the mold, the semi-circular portion of the bearing portion 8 is sheared along the step 9, and the main body portion 1 and the half-divided bearing portion 8, The cap portion 2 and the cap portion 2 are arranged in a line.

Then, when the whole sintered body was compressed, the embodiment-
As the density increases, it is shaped as in No. 1 and the shear surface 5a
The step 9 surface, and the semicircular end surface of the main body 1 and the outer peripheral surface of the half-divided bearing portion 8 are closely joined. [Embodiment 3] FIG. 10 is a cross-sectional view of a connecting rod that has been plastically worked with a mold using a large-diameter core that is not divided. When the taper pin is inserted into the bearing hole 7a,
The planned dividing surface 5 is cracked and can be divided. As in the case of Example-1 and Example-2, the divided surface has waviness and wavy unevenness, and good assembling property. The bearing portion 8 separates from the main body portion 1 when a strong impact is applied, but when used in alignment, the bearing portion 8 is pressed by the cap portion 2 and does not move. [Embodiment 4] In FIG. 11, the shearing of the semicircular bearing portion 8 is the same as above, but the large-diameter core of the plastic working die is divided into upper and lower parts as shown in FIG. It is a large-end sectional view in the case where a die having a structure in which a gap 12C is sometimes formed is used and a surplus thickness 7b is formed in a bearing hole 7a. By doing so, the semicircular bearing portion 8 plastically flows into the inner diameter of the bearing hole 7a, so that the material of the main body portion 1 also follows, and as a result, the main body portion 1 and the semicircular bearing portion 8 are firmly bonded. It becomes a state.

Since the main body portion 1 has a high density, the strength of the connecting rod is high, and the pores of the bearing portion and the cap portion are impregnated with oil and have excellent lubricity.

[0032]

As described above, according to the manufacturing method of the present invention, the upper and lower end faces of each of the upper and lower end faces of the sintered body having a stepped shape in which the main body portion and the cap portion are displaced from each other along the planned dividing surface. Is compressed in a direction in which the two are aligned, that is, a direction in which the deviation is zero, and sheared from the planned dividing surface, the planned dividing surfaces of both members are opposed to each other, and the whole is compressed to plastically deform until the dividing surfaces come into close contact with each other. From the above, according to the method of the present invention, the workability of the workpiece during fabrication is good, the shear load is low, and due to the appropriate adhesiveness of the divided end faces of the plastically worked body, both member fixing means at the time of bolt hole machining etc. Besides, it is possible to obtain a connecting rod which is excellent in workability of assembling and assembling accuracy due to undulations and wavy irregularities generated by plastic working.

Further, by using a sintered body in which semicircular bearings are provided in different steps so as to form a large end bearing in either the main body portion or the cap portion, the semicircular bearing portion is formed in the mold. According to the method of shearing and plastically deforming similar to the above, in addition to the same effects as described above, the characteristics of the main body portion, the bearing portion and the cap portion can be changed, and the connecting rod can be given individuality, so that the device used There is an effect that it contributes to the performance improvement of.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mold device for explaining a plastic working method of the present invention.

FIG. 2 is a top view of a connecting rod.

FIG. 3 is a vertical cross-sectional view of a sintered body.

FIG. 4 is a vertical cross-sectional view for explaining a plastic working die structure and plastic working.

FIG. 5 is a vertical sectional view of a mold for explaining a state where a sintered body is plastically processed.

FIG. 6 is a top view of a connecting rod.

FIG. 7 is a top view of a connecting rod.

FIG. 8 is a vertical sectional view of a sintered body.

FIG. 9 is a perspective view of a sintered body.

FIG. 10 is a vertical sectional view of a plastically worked body.

FIG. 11 is a vertical cross-sectional view of a large end portion of a plastically worked body having a surplus.

[Explanation of symbols]

1 Main body 2 Cap section 3 Sintered body Planned division surface 5a Shear surface 6 small end 7 Large end 7a Bearing hole 7b extra thickness 8 bearing 9 steps 10 dies 11 small diameter core 12 Large core 12d protrusion 21 Lower punch 31 Upper first punch 32 Upper second punch 40 Upper Ram 41 hydraulic cylinder 51 shear plane 91 extra thickness

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Claims (6)

(57) [Claims] 1. A main body portion and a cap portion of a connecting rod are compacted into an integrally molded body having a deviation from each other along a dividing surface to obtain a sintered body, and the sintering is performed in a direction in which the deviation is zero. A method for manufacturing a sintered connecting rod, comprising compressing a body in a mold to apply shear to a planned dividing surface, and then pressing and plastically deforming the divided surface until they come into close contact with each other. 2. A main end portion and a cap portion of the connecting rod are divided into one and formed by integrally mounting a large end bearing having a deviation from each other along a planned division surface, and the other end is formed into a large end. The bearing is excluded from the molding, and the main body and the cap are divided into two parts, and the divided surfaces of the sintered body are opposed to each other. Then, the planned dividing surfaces of the main body portion and the cap portion are opposed to each other, and the respective dividing planned surfaces and the outer peripheral surface of the bearing and the inner peripheral surface of the opposing member are pressed and plastically deformed. A method for manufacturing a sintered connecting rod. 3. The method for manufacturing a sintered connecting rod according to claim 2, wherein the main body portion and the cap portion are made of different alloys. 4. The method for manufacturing a sintered connecting rod according to claim 1, wherein a surplus due to plastic deformation is formed in the large end shaft hole. 5. The method for manufacturing a sintered connecting rod according to claim 1, wherein a sintered body having a cap portion having a height smaller than that of the main body portion or a density lower than that of the main body portion is used. . 6. The method for manufacturing a sintered connecting rod according to claim 1, wherein the main body portion and the cap portion are made of an aluminum alloy.