JPH08284945A - Manufacture of split type connecting rod - Google Patents

Abstract

PURPOSE: To prevent an installation to a crank pin from hindrance even if the junction faces of a connecting rod and a cap are slid from the diameter line of the large end and the inside periphery of the cap when forming the connecting rod and the cap is junction condition by the forging of a connecting rod body material and a cap material. CONSTITUTION: In the forging process, an axial groove 8 is made over the region A where the formation of the junction faces 6 and 7 is forecast, at the large end 2B of the connecting rod 2 and the inside periphery of the cap 3, and even if the junction faces 6 and 7 are slid from the diameter line C of the large end part 2B and the inside periphery of the cap 3, those inside edges are stayed within the axial groove 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting rod used in a piston engine, a piston pump or the like, and more particularly to a connecting rod body having a small end portion, a semi-annular large end portion and a rod portion integrally connecting both end portions thereof. , A method of manufacturing a split connecting rod comprising a semi-annular cap that is separably joined to its large end.

[0002]

2. Description of the Related Art Conventionally, when a split type connecting rod is manufactured, a V-shaped notch for breaking is formed on the inner peripheral surface of the large end of an integrally cast connecting rod, and at this boundary, the connecting rod body and the cap are broken. It is known to split (see, eg, US Pat. No. 4,569,109).

However, in the manufacturing method as described above, a large impact force must be applied when the connecting rod is broken, and the fracture surface is not constant, which may cause a partial decrease in strength of the connecting rod body and the cap. There is.

Therefore, the present applicant separately forms the connecting rod body material and the cap material, forms the connecting rod body and the cap in which the joint surfaces are brought into close contact with each other by forging from these materials, and finally separates the joint surfaces. And previously proposed a method for obtaining a split connecting rod (Japanese Patent Application No. 6-3
33282).

According to the method proposed above, a wrinkle-shaped joint surface useful for positioning and joining the connecting rod body and the cap can be formed during forging, and after the forging, the connecting rod body and the cap are relatively light. The impact force can separate the joining surfaces, and thus the high quality split connecting rod can be efficiently manufactured.

[0006]

However, the following problems have been clarified in the method proposed above. That is, considering the mountability of the connecting rod body and the cap to the crankpin, it is desirable that these joint surfaces are located on the diameter line of the large end portion and the inner peripheral surface of the cap. Since the amount of movement is uneven,
The point is that it is extremely difficult to align the formed joint surface with the diameter line.

The present invention has been made in view of such problems, and even if the connecting surfaces of the connecting rod body and the cap are formed deviating from the diameter line of the large end portion and the inner peripheral surface of the cap during forging. An object of the present invention is to provide a method for manufacturing the split type connecting rod, in which the connecting rod body and the cap, which are divided later, can be mounted on the crank pin without any trouble.

[0008]

In order to achieve the above object, the present invention is to press individually molded connecting rod body material and cap material in a series of cavities of a forging die so that the joining surfaces are joined to each other. It includes a forging step of forging the closely attached connecting rod body and the cap, and a separation step of separating the joint surface of the connecting rod body and the cap, and in the forging step, on the large end of the connecting rod body and the inner peripheral surface of the cap, It is characterized in that an axial groove is formed over an area where the joining surfaces are to be formed.

In addition to the above characteristics, the present invention has a second characteristic that the bottom surface of the axial groove is formed flat.

[0010]

According to the first feature of the present invention, when the joint surface of the connecting rod body and the cap is formed in the forging step, the shaft is formed on the large end portion and the inner peripheral surface of the cap over the expected formation area of the joint surface. Since the directional groove is formed at the same time, even if the joining surface is slightly deviated from the diameter line of the inner peripheral surface, the inner end edge of the joining surface remains in the axial groove. Therefore, when the connecting rod body and the cap are separated and then mounted on the outer periphery of the crankpin, it is possible to avoid the inner end edge of the joint surface of the connecting rod body and the cap from interfering with the outer peripheral surface of the crankpin.

Further, according to the second feature of the present invention, even when the joint surface is displaced from the diameter line of the inner peripheral surface, there is a disadvantage in strength between the joint surface and the bottom surface of the axial groove. It is possible to avoid the formation of sharp acute-angled portions.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, the structure of the split connecting rod manufactured by the method of the present invention will be described with reference to FIG. The connecting rod 1 includes a connecting rod body 2 and a cap 3. The connecting rod body 2 has a small eye-shaped end 2 _S ,
It has a semi-annular large end portion 2 _B and a rod portion 2 _R integrally connecting them, and the piston 4 is connected to the small end portion 2 _S via a piston pin 5. Cap 3 has no a semi-annular as in the large end portion 2 _B, joining surfaces 6, 7 facing each of these big end 2 _B and the cap 3 has a meshing wrinkled uneven portion from each other. Further, on the inner peripheral surfaces of the large end portion 2 _B and the cap 3, an axial groove 8 is formed so as to face the inner end edges of the joint surfaces 6 and 7. Screw holes 11 and even more at both ends of the cap 3 through holes 10, 10 for inserting bolts 9 and screwing the bolt 9 at both end portions of the large end portion 2 _B,
11 are drilled respectively.

Thus, these large end portion 2 _B and cap 3
Are joined to the outer peripheral surface of the crankpin 12 of the crankshaft so as to be rotatable relative to each other, and the joint surfaces 6 and 7 are aligned with each other.
Are combined by.

A method of manufacturing the split connecting rod 1 will be described below with reference to FIGS.

First, as shown in FIGS. 2 and 3, a connecting rod body material 02 and a cap material 03 each having a shape similar to that of the connecting rod body 2 and the cap 3 are individually molded from Al alloy powder. At that time, the following powder molding die 13 is used.

The mold 13 is made of a connecting rod body material 02.
And a die 16 in which first and second cavities 15 and 16 respectively corresponding to the shape of the cap material 03 are independently provided, and upper and lower punches 17 and 18 fitted into the cavities 15 and 16 from above and below, respectively. ; 19,
20 and the first cavity 1 fixed to the lower punch 18.
4 and a small-diameter core 21 which penetrates the core 4.

Thus, the first and second cavities 14, 1
5 is filled with Al alloy powder, and these are pressed and compressed by upper and lower punches 17, 18; 19, 20 to form connecting rod body material 02 and cap material 03, and then these are sintered furnace not shown. And sinter. The sintering may be pre-sintering with a relatively low sintering temperature.

Next, as shown in FIGS. 4 to 6, the connecting rod body 2 and the cap 3 are formed from the connecting rod body material 02 and the cap material 03 by forging. In the molding, the following forging die 22 is used.

The die 22 is fixed to a die 24 having a series of cavities 23 corresponding to the shape of the connecting rod 1, upper and lower punches 25 and 26 fitted into the cavities 23 from above and below, and a lower punch 26. The small-diameter core 27 and the large-diameter core 28 penetrate the cavity 23, and the small-diameter core 27 is arranged so as to correspond to the pin hole of the small end portion 2 _S. Edge 2
It is arranged so as to correspond to the inner peripheral surfaces of _B and the cap 3. Further, the large-diameter core 28 has a pair of axial ridges 29, 29 arranged on the outer peripheral surface thereof, which are arranged over the predicted formation region A of the joint surfaces 6, 7 of the connecting rod body 2 and the core 3.
The top surface of the axial ridge 29 is a flat surface.

In the forging, first, the connecting rod body material 02 and the cap material 03 are put in the cavity 23 in a regular facing state as shown in FIG. 4, and then they are shown in FIGS. 5 and 6. Upper and lower punches 25,2
By applying pressure with 6, the connecting rod body 2 and the cap 3 in which the joint surfaces 6 and 7 are in close contact with each other are molded.
At this time, the inner peripheral surface of the large end 2 _B and the cap 3, since axial groove 8 over the formation prediction area of the joint surface 6, 7 by the axial projection 29 of the large diameter core 28 is formed, Even if the joint surfaces 6 and 7 are formed deviating from the diameter line C of the large end portion 2 _B and the inner peripheral surface of the cap 3 due to the difference in the movement amount of each of the materials 02 and 03, the inner surface Axial groove 8 on the edge
It does not deviate outside. Moreover, the bottom surface of the axial groove 8 is
Since the flat surface of the axial ridge 29 is formed flat, even if the joining surfaces 6 and 7 deviate from the diameter line C as described above, the joining surfaces 6 and 7 and the bottom surface of the axial groove 8 are formed. It is possible to avoid that the corner portion sandwiched between is sharp.

Further, as shown in FIG. 7, the joint surfaces 6 and 7 are compressed by the compression reaction forces from the outer peripheral surface of the large-diameter core 28 and the inner peripheral surface of the cavity 23 due to the compressive deformation of the materials 02 and 03.
Wrinkle-shaped uneven portions that mesh with each other are formed, and in particular, the large-diameter core 2
Since the axial ridge 29 of No. 8 strongly compresses the inner peripheral surface on the large end side of the materials 02, 03, it greatly contributes to the formation of wrinkle-like irregularities at the joint surfaces 6, 7.

After forging the connecting rod body 2 and the cap 3, the cap 3 is provided with a bolt insertion hole 10 and the large end portion 2 _B is provided with a screw hole 11 while maintaining the joined state of the joining surfaces 6 and 7. Further, finishing processing is performed on the large end portion 2 _B and the inner peripheral surface of the cap 3 as required.

After the above processing, impact force is applied to the connecting rod body 2 and the cap 3 to separate the joint surfaces 6 and 7 thereof as shown in FIG. 7, but the joint surfaces 6 and 7 that are closely formed by forging. Can be easily separated with a relatively small impact force.

The connecting rod body 2 and the cap 3 thus separated are mounted on the outer periphery of the crank pin 5 as described above (see FIG. 1), and their joint surfaces 6, 7 are attached.
Even if is displaced from the diameter line C of the large end portion 2 _B and the inner peripheral surface of the cap 3, the inner peripheral edges of the large end portion 2 _B and the cap 3 are prevented from interfering with the outer peripheral surface of the crank pin 5 by the axial groove 8. Therefore, it can be mounted on the crank pin 5 without any trouble. Moreover, since the joint surfaces 6 and 7 have wrinkle-shaped irregularities, the proper joint positions of the joint surfaces 6 and 7 can be secured by the meshing of the irregularities.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist thereof. For example, the connecting rod body material 02 and the cap material 03 can also be formed by die casting an Al alloy. It is also possible to preform the axial groove 8 when forming the connecting rod body material 02 and the cap material 03.

[0027]

As described above, according to the first feature of the present invention, the individually molded connecting rod body material and cap material are pressed in a series of cavities of the forging die to bring the joint surfaces into close contact with each other. A forging step of forging the connecting rod body and the cap that were made to include a separation step of separating the joint surface of the connecting rod body and the cap, in the forging step, the large end of the connecting rod body and the inner peripheral surface of the cap,
Since the axial groove is formed over the formation predicted region of the joint surface, even if the joint surface of the large end portion and the cap is formed deviating from the diameter line of the inner peripheral surface of the joint surface during forging, The inner edge may be retained within the axial groove. Therefore, when the connecting rod body and the cap are separated and attached to the crankpin, it is possible to avoid the inner edge of the joint surface from interfering with the outer peripheral surface of the crankpin, and to attach them without any trouble.

According to the second aspect of the present invention, since the bottom surface of the axial groove is formed flat, the joint surface of the large end portion and the cap is formed deviating from the diameter line of the inner peripheral surface thereof. However, it is possible to prevent a sharp acute angle portion from being formed between the joint surface and the bottom surface of the axial groove, and it is possible to prevent the corner portion from being damaged at the time of bolt connection.

[Brief description of drawings]

FIG. 1 is a front view of a connecting rod manufactured by the method of the present invention.

FIG. 2 is a plan view showing a powder forming process of a connecting rod.

3 is a sectional view taken along line 3-3 of FIG.

FIG. 4 is a plan view showing a state before the forging process of the connecting rod is started.

FIG. 5 is a plan view showing a state where the connecting rod forging process is completed.

6 is a sectional view taken along line 6-6 of FIG.

FIG. 7 is a perspective view showing a separated state of the connecting rod body and the cap.

[Explanation of symbols]

A Bonding surface formation predicted area C Diameter line 02 Connecting rod material 03 Cap material 1 Connecting rod 2 Connecting rod body 2 _B Large end 2 _S Small end 2 _R Rod 3 Cap 8 Axial groove 22 Forging die

Claims (2)

[Claims] 1. A connecting rod body (2) having a small end (2 _S ), a semi-annular large end (2 _B ), and a rod portion (2 _R ) integrally connecting both ends thereof, and a large end thereof. In a method for manufacturing a split connecting rod, which comprises a semi-annular cap (3) that is separably joined to a portion (2 _B ), a separately formed connecting rod body material (02) and a cap material (03) are forged. A forging step of forging a connecting rod body (2) and a cap (3) in which a joining surface (6, 7) is brought into close contact with each other by pressurizing in a series of cavities (23) of a mold (22); 2) and a separation step of separating the joint surfaces (6, 7) of the cap (3), in the forging step, the large end portion (2) of the connecting rod body (2) is included.
_B ) and the inner peripheral surface of the cap (3), the groove (8) in the axial direction over the predicted formation area (A) of the joint surfaces (6, 7).
A method for manufacturing a split-type connecting rod, which comprises molding. 2. The method for manufacturing a split connecting rod according to claim 1, wherein the bottom surface of the axial groove (8) is formed flat.