JP2001003924A - Manufacture of connecting rod for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve assembling accuracy of both by forming a material with a rod body and a cap integrated together, dividing it with its treated at low temperature, returning it to a normal temperature, and brushing the divided surfaces. SOLUTION: A connecting rod material 4 is cold-forged from a preformed material 3, end faces of large and small end parts 5, 6 are ground, the inside face of the large end port 6 is ground, and notches 7 and connecting holes 8 are machined. The material 4 is suspended, and the large end part 6 is dipped in liquid nitrogen in a low-temperature treatment vessel 9 to be fractured and divided into a rod body 1 and a cap 2. Then, the both of them are laid on a pallet 12a circulating in a temperature-raising treatment vessel 12 having hot water put therein to be returned into a normal temperature, and the divided faces are brushed by a nylon brush 13 with abrasive grains to remove fine projections to be easily chipped off. The divided surfaces are cleaned and air blown, the cap 2 is fastened to the rod body 1 via the connecting holes 8 by a bolt 14, a bush is press fitted into the small end 5, and the bush and the inside face of the large end 6 are finished. This constitution can improve the assembling accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an engine connecting rod comprising a rod body and a cap.

[0002]

2. Description of the Related Art Conventionally, according to Japanese Patent Application Laid-Open No. 63-195408, a connecting rod material having a shape in which a rod body and a cap are integrated is formed, and the connecting rod material is combined with the rod body in a state where the connecting rod material is subjected to a low-temperature treatment. 2. Description of the Related Art A method for manufacturing a connecting rod for an engine, which is divided into a cap and a cap, is known.

[0003]

According to the above conventional method, the connecting rod material is brittlely broken by a relatively small load by the low-temperature treatment, and is divided into a rod body and a cap. Then, the split surface between the rod body and the cap has a brittle fracture surface with unevenness, and the engagement of the unevenness can ensure the assembly accuracy of the rod body and the cap.

[0004] However, minute projections overlapping with irregularities may be formed on the split surface, and when the cap is mounted on the rod body, the minute projections are missing and bite between the split surfaces of the rod body and the cap. In some cases, the cap cannot be accurately assembled to the rod body.

In view of the above, the present invention provides a method of manufacturing a connecting rod for an engine in which minute projections on a split surface are removed to improve the assembling accuracy of a rod body and a cap. It is an issue.

[0006]

Means for Solving the Problems In order to solve the above problems,
The present invention relates to a method of manufacturing a connecting rod for an engine comprising a rod body and a cap, wherein the connecting rod material is formed by molding a connecting rod material having a shape in which the rod body and the cap are integrated, and subjecting the connecting rod material to a low-temperature treatment. Is divided into a rod body and a cap. After dividing the connecting rod material, the rod body and the cap are returned to room temperature, and then the split surface between the rod body and the cap is brushed.

[0007] As described above, the fine projections on the split surface can be removed by brushing the split surface, and when the cap is mounted on the rod body, the fine projections bite between the two split surfaces, so that the rod body and the rod main body can be removed. It is possible to prevent the accuracy of assembling with the cap from deteriorating.

It is conceivable that brushing is performed immediately after the division of the connecting rod material. However, immediately after the division, the low temperature is so low that the water vapor in the air freezes on the cut surface, making it impossible to remove fine projections properly. On the other hand, according to the present invention, since the brushing is performed after the temperature is returned to the normal temperature, the minute projections can be efficiently removed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a manufacturing process of an engine connecting rod comprising a rod body 1 and a cap 2. In manufacturing a connecting rod, first, a rod body 1 and a cap 2 as shown in FIG. 1 (b) are integrally formed from a preform material 3 shown in FIG. 1 (a), which is formed of steel for cold forging having the following composition. The connecting rod material 4 having the formed shape is formed by cold forging. The steel for cold forging is C: 0.
05-0.25%, Si: 0.35-0.60%, M
n: 0.20 to 1.30%, Cr: 0.15 to 0.60
%, And S: 0.030 to 0.100%, T
e: 0.005 to 0.040%, Pb: 0.03 to 0.
30%, Bi: 0.03 to 0.20%, Ca: 0.00
One or two selected from among 0.05 to 0.0050%
The following (1) and (2) formulas containing at least one species and the balance consisting of Fe: 19 ≦ 85 (% C) +9 (% Si) +3 (% Mn) +5 (% Cr) ≦ 25… ( 1) 100 (% C) +3 (% Si) +3 (% Mn) -9 (% Cr) +100 (% S) -20 (% Te) ≦ 23 (2) Excellent cold forgeability and fatigue strength.

Next, the end grinding of the small end 5 and the large end 6 of the connecting rod material 4 and the internal grinding of the large end 6 are performed, and as shown in FIG. The processing of the notches 7 and 7 for dividing the inner surface and the processing of the coupling holes 8 and 8 for the caps on both sides of the large end 6 are performed.

When the above machining is completed, FIG.
As shown in (d), while the connecting rod material 4 is hung on a chain conveyor (not shown), the large end 6 is immersed in liquid nitrogen in the low temperature processing tank 9 to subject the large end 6 to low temperature processing. Then, the large end 6 is broken, and the connecting rod material 4 is divided into the rod body 1 and the cap 2 as shown in FIG. In the low-temperature treatment, the large end 6 is cooled so that the temperature of the large end 6 is maintained at −130 ° C. or less, which is a brittle transition temperature, at the time of division.

The dividing of the connecting rod material 4 is performed by using a dividing device 10 shown in FIGS. This dividing device includes a base 101 and a jig base 102 provided on the base 101. The small end 5 is connected to the jig base 102 with the connecting rod material 4.
A groove-shaped support member 103 that is slidable in the longitudinal direction and does not swing in the direction perpendicular to the longitudinal direction.
And a support plate 104 that supports the cap-side half of the large end 6.
And a support plate 105 for supporting the main body side half of the large end 6. The support plate 104 is fixed to the jig base 102, while the support plate 105 is guided by a guide groove 106 formed in the jig base 102 and is slidable in the longitudinal direction of the connecting rod material 4. The springs 107, 107 on both sides stretched between the support plate 104 and the support plate 104 bias the support plate 104. On both support plates 104, 105, semicircular pieces 108, 109 inserted into the inner periphery of the large end 6 are erected. A wedge member 1011 vertically moved by a hydraulic cylinder 1010 attached to the base 101 between the two pieces 108 and 109.
The surface of the wedge member 1011 on the side of the bridge 109 is formed as an overhanging inclined surface, and when the wedge member 1011 is moved downward, the bridge 109 is disengaged from the bridge 108 against the urging force of the spring 107. It is made to be pushed in the direction to separate. The jig table 102 is further provided with a cylinder 1012 for clamping the half of the large end 6 on the cap side between the jig 102 and the bridge 108.
And a pair of stoppers 1014 and 1414 for preventing the rod body after splitting from jumping out.
1014 are provided.

When the connecting rod material 4 is divided, the small end portion 5 of the connecting rod material 4 which has been subjected to the low-temperature treatment is engaged with the support member 103 by an automatic machine such as a robot (not shown), and the inner peripheral portion of the large end portion 6 is formed. The pieces 108 and 109 are set on the jig table 102 so that the pieces 108 and 109 are inserted into the pieces. Next, the clamp member 101
After closing 3, the wedge member 1011 is moved downward. According to this, the main body side half of the large end portion 6 is pressed toward the small end portion 5 via the piece 109, and the large end portion 6 starts from the notches 7, 7.
Is broken brittlely, and the connecting rod material 4 is divided into the rod body 1 and the cap 2.

When the division is completed, the rod body 1 and the cap 2 are placed on a pallet 12a which circulates in a heating tank 12 containing hot water by an automatic machine (not shown), as shown in FIG. The rod body 1 and the cap 2 are placed and a temperature raising process for returning the temperature to room temperature is performed. Next, as shown in FIG. 1 (g), the split surface between the rod body 1 and the cap 2 is brushed with a nylon brush 13 containing abrasive grains.

Here, the split surface between the rod body 1 and the cap 2 has a brittle fracture surface with irregularities as shown in FIG. Then, as shown in FIG. 5A, minute projections may be formed on the split surface so as to overlap with the irregularities. In this state, when the cap 2 is attached to the rod body 1, the minute projections are missing. The rod body 1 and the cap 2 bite between the split surfaces, and the assembling accuracy of the rod body 1 and the cap 2 deteriorates. On the other hand, when brushing is performed as described above, FIG.
As shown in (B), the minute projections that are easily chipped are removed, and the above-mentioned problem is prevented.

After brushing, cleaning of the split surface and air blowing are performed. Next, the cap 2 is attached to the rod body 1 and FIG.
As shown in (h), the bolts 14 are used for fastening in the coupling holes 8. Then, a bush (not shown) is press-fitted into the small end portion 5 to finish the inner surface of the bush and the inner surface of the large end portion 6.

As shown in FIG. 4, the coupling hole 8 is composed of a screw hole 81 on the rod body 1 side and a bolt insertion hole 82 extending from the screw hole 81 to the cap 2 side. Then, the bolt insertion hole 82 is inserted into the large-diameter portion 82 near the outer surface of the cap 2.
a and a stepped portion 82b in the cap 2 with respect to the large-diameter portion 82a.
And a stepped hole having a small diameter portion 82c extending to the screw hole 81 side. The diameter a of the small diameter portion 82c is set to a value larger than the outer diameter b of the bolt 14 and smaller than the root diameter c of the screw hole 81. The difference between the root diameter c of the screw hole 81 and the outer diameter b of the bolt 14 is about 0.1 mm.

When the coupling hole 8 is formed, the small diameter portion 82c is also formed simultaneously with the pilot hole of the screw hole 81, so that the coaxiality between the pilot hole of the screw hole 81 and the small diameter portion 82c is ensured. After that, tapping of the screw hole 8 is performed. Since the small diameter portion 82c is smaller than the root diameter c of the screw hole 81, that is, the outer diameter of the tap, a shallow spiral groove 82d is formed on the inner surface of the small diameter portion 82c. .

When the cap 2 is fastened to the rod body 1, the bolt 14 is screwed into the screw hole 81 from the cap 2 through the bolt insertion hole 82. In this case, bolt 14
Of the bolt insertion hole 82 with respect to the rod body 1
Of the cap 2 with respect to the
mm or less. Here, the average pitch of the primary unevenness excluding the minute unevenness of the split surface is about 0.15 mm,
The unevenness of the split surface of the cap 2 does not shift to a position facing the unevenness different from the corresponding unevenness of the split surface of the rod body 1. Thus, the cap 2 can be accurately fastened to the rod body 1 in a state where the unevenness of the split surface of the cap 2 is engaged with the corresponding unevenness of the split surface of the rod body 1.

[0020]

As is apparent from the above description, according to the present invention, the minute projections on the split surface between the rod body and the cap can be removed by brushing, and the assembling accuracy between the rod body and the cap can be reduced. It can be prevented from being deteriorated by the biting of the minute projections into the projections, and the assembling accuracy can be improved.

[Brief description of the drawings]

1A to 1H are views showing a manufacturing process of a connecting rod.

FIG. 2 is a plan view of a dividing device.

FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is an enlarged cross-sectional view of a connecting portion between a rod body and a cap.

5A is a graph showing a measurement result of unevenness of a part of the split surface before brushing, and FIG. 5B is a graph showing a measurement result of unevenness of the part of the split surface after brushing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rod main body 2 Cap 4 Connecting rod material 10 Splitting device 13 Brush

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ryuji Soga 1-10-1 Shinsayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. F-term (reference) 3J033 AC01 EA02

Claims (1)

[Claims] 1. A method of manufacturing a connecting rod for an engine comprising a rod body and a cap, comprising: forming a connecting rod material having a shape in which the rod body and the cap are integrated; and performing a low-temperature treatment on the connecting rod material. An engine connecting rod for dividing a material into a rod body and a cap, wherein after dividing the connecting rod material, the rod body and the cap are returned to room temperature, and then the split surface between the rod body and the cap is brushed. Manufacturing method.