JPH09201640A - Manufacture of con'rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a high-precision con'rod by surely dividing a con'rod cap from the con'rod body without destructing the holder even if a bearing bore diameter is small. SOLUTION: A steel preliminarily cut in accordance with the size of a con' rod C is heated to a temperature suitable for forging and formed into a required con'rod shape by forging; it is then cooled after forging, with shotblasting applied; and machining is performed for the thickness direction, bore diameter and bolthole of the large and small ends CL, CS of the con'rod C. Then, a dividing holder H1 supported by the die cushion method is inserted into the large end CL and held, with a tapered pin D, E inserted from the upper and lower directions inside this holder H1. Further, one tapered pin is pressurized to separately form the con'rod body C1 and the con'rod cap C2; after the separated con'rod body C1 and the cap C2 are integrated with the bolt tightened, finish machining is performed; and the con'rod body C1 and the cap C2 are thereby manufactured integrally by forging.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a connecting rod, and more particularly, to a method of manufacturing a connecting rod with high accuracy in which a connecting rod cap is integrally formed by splitting from a connecting rod body after forming by forging using a steel material. Is.

[0002]

2. Description of the Related Art Conventionally, for a forged connecting rod used in an internal combustion engine, a method of separately manufacturing a connecting rod body and a cap of the connecting rod, and a method of integrally manufacturing both the connecting rod body and the connecting rod cap from the beginning. There is. In this supplementary manufacturing method, the connecting rod body and the connecting rod cap are divided by machining.

[0003]

In the conventional connecting rod manufacturing method described above, the method of cutting the connecting rod cap integrally forged on the large end portion of the connecting rod body requires cutting steps and balance adjustment. It has become a thing. In order to improve this method, a method has been proposed in which the connecting rod cap is integrally forged, then a split collar is inserted into the bearing hole at the large end, and a wedge is driven between the split collars to split the split collar into two. For example, JP-A-58-37311
Is disclosed in Japanese Patent Application Laid-Open Publication No. HEI 9-203 (1995). However, the split collar used in this method is L-shaped, and when a wedge is pressed into this split collar, bending stress concentrates on the bending position of the split collar, and it is easy to break at this bending position. If the bearing hole diameter is small, it is easily broken, which is not suitable for mass production. The present invention solves the problems of the conventional connecting rod manufacturing method described above, and reliably separates the connecting rod cap from the connecting rod body without breaking the holder even if the bearing hole diameter is small, and easily manufactures a highly accurate connecting rod. It is an object of the present invention to provide a method for producing a connecting rod that can be manufactured.

[0004]

In order to achieve the above object, the method of manufacturing a connecting rod of the present invention requires heating a steel material previously cut according to the size of the connecting rod to be manufactured to a temperature suitable for forging. Forging process of forming into a connecting rod shape by forging, and after forging it is cooled and subjected to shot blasting, the thickness direction of the large and small ends of the connecting rod, the inner diameter,
A rough machining process for drilling bolt holes, and then inserting and supporting a holder for division supported by the die cushion method inside the large end, insert a taper pin from the vertical direction inside this holder, and insert one taper pin. It consists of a series of steps: a dividing step of pressurizing and dividing into a connecting rod body and a connecting rod cap, and a finishing step in which the divided connecting rod body and connecting rod cap are integrally united and bolts are then machined after finishing. The connecting rod body and the connecting rod cap are integrally manufactured by forging.

According to the method of manufacturing the connecting rod of the present invention having the above-mentioned structure, the holder to be inserted into the large end portion of the connecting rod is supported by the die cushion type, and the taper pin is vertically inserted into the holder to bend the bending stress of the holder. Since it is not concentrated, the division of the large end can be reliably performed with a small load without breaking the holder, and it is suitable for mass production.

In this case, a hole is formed between the connecting rod cap and the connecting rod body, which is divided between a rough machining step of rough machining the large end of the connecting rod formed in the forging step and a dividing step using a holder. A connecting bolt can be inserted into the bolt hole and temporarily tightened so that the connecting rod cap does not separate from the connecting rod body in the dividing step.

According to the method of manufacturing the connecting rod of the present invention having the above-mentioned structure, the connecting rod cap portion and the connecting rod body are temporarily tightened with bolts before the large end portion is divided. Since this is not done, the combination of the connecting rod cap and the connecting rod body can be performed reliably and easily.

Further, after hot-coining the connecting rod formed in the forging process, shot blasting in the rough machining process can be performed.

The manufacturing method of the connecting rod of the present invention having the above-mentioned structure can improve the accuracy after manufacturing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a method for manufacturing a connecting rod according to the present invention will be described below with reference to the drawings. In the present invention, a steel material is used as a connecting rod material, and the connecting rod is cut in advance according to the size of the connecting rod to be manufactured. In this case, the material diameter and cutting length are determined according to the shape and volume of the formed connecting rod.

Next, the cut steel material is heated to a temperature suitable for forging. The heating temperature is predetermined depending on the hot condition, the warm condition, the material of the steel material, and the like. Then, the cut steel material heated to an appropriate temperature is forged into the required connecting rod shape. In this forging step, the shape of the connecting rod C that is almost formed from steel is prepared, but hot coining may be performed after forging if necessary.

Next, this is cooled and shot blasting is applied, and the large and small ends C of the connecting rod are subjected to the rough machining process.
L and CS are formed by cutting or the like so as to have a predetermined dimension in the thickness direction, the inner diameter of the bearing hole CH is designed to have a design dimension, and the large end CL is divided to connect the connecting rod body C1 and the connecting rod. When it is formed on the cap C2 and is rotatably attached to the crank shaft via a metal or the like, a bolt hole for fixing the connecting rod body and the connecting rod cap by bolting is drilled. If necessary, cold coiling may be performed before processing the large and small ends in the thickness direction.

Next, the bolt is inserted into the bolt hole drilled in the connecting rod and temporarily fastened with a nut. This prevents the connecting rod body C1 and the connecting rod cap C2 from being separated from each other in the next step. Therefore, this temporary bolt tightening has a slight gap so that the connecting rod cap can be separated from the connecting rod body. The temporary tightening with this bolt may be omitted.

The connecting rod is set on the dividing table T. This split table T is supported on the lower surface by a spring and a hydraulic type support device B by a die cushion method, whereby the connecting rod is held on the split table even if pressure is applied to the connecting rod on the split table from above. The split table can be moved downward in this state so that bending stress is not concentrated on a part of the holder.
A holder H to be inserted into a bearing hole CH formed at the large end is integrally formed on this split table. Therefore, this holder is equal to the inner diameter of the bearing hole and has a split shape as shown in the figure. The split holders are integrated with the split holders H1 and H2.

When the connecting rod C is set on the dividing table T, the holders H1 and H2 are inserted and supported in the bearing holes CH of the connecting rod. Tapered pin insertion holes P1 and P2 are formed in the holder from both upper and lower directions, and a lower tapered pin D protruding upward from the base is inserted from the lower part of the holder. While making the taper angle of the taper-shaped taper pin insertion hole P2 and the taper angle of the lower taper pin D in this holder equal,
An upper taper pin E which vertically moves from above the lower taper pin D is provided so as to face the lower taper pin D. The taper angle of the upper taper pin E and the taper angle of the taper pin insertion hole P1 are made equal. In the illustrated embodiment, the angles are the same in both directions of the dividing direction, but this taper angle may be formed on one side of the connecting rod cap.

The upper taper pin E is applied with a pressing method such as hydraulic pressure, a weight dropping method, an air hammer method, or any other method to apply a load enough to divide the large end of the connecting rod. It may be applied slowly. The tips of the upper and lower taper pins that are inserted from the top and bottom into the taper insertion hole of the holder are located in the center of the holder respectively, which prevents the bending stress applied to the holder from concentrating at one point when the large end is split. Prevent the destruction of.

Therefore, when the upper taper pin is lowered from the upper part of the connecting rod supported by the holder of the split table, the pressure causes the taper pin to be inserted into the holder from both upper and lower directions, and the force from above is evenly applied to the left and right holders at the taper angle. It is converted laterally into the holder and applied evenly to the holder from above and below, so that the bending stress is not concentrated on the connecting portion of the holder with the dividing table. In this way, the vertical load is converted into the lateral load by the taper pin, so that the large end portion can be broken (split) with a small load.

After the connecting rod main body and the connecting rod cap are divided and formed in this way, the connecting rod main body and the connecting rod cap are re-aligned and a bolt is inserted between the opposing bolt holes, or a temporarily tightened bolt is fastened. To do. After that, finish machining is performed to obtain a highly accurate product.

A stopper for the upper taper pin may be provided to prevent the lower end of the upper taper pin from dropping at a position where the large end of the connecting rod is divided when the upper taper pin is lowered. If one method is shown, as shown in FIG. 2, a stopper is provided on the side of the upper taper pin, and when the stopper is lowered to a fixed position of the upper taper pin, the stopper is brought into contact with the stopper protruding from the lower part to perform positioning.

[0020]

According to the method of manufacturing the connecting rod according to the first aspect of the present invention, the holder to be inserted into the large end of the connecting rod is supported by the die cushion type, and the taper pin is vertically inserted into the holder to bend the holder. Since the bending stress is not concentrated on the portion, there is an advantage that the division of the large end portion can be surely performed with a small load without breaking the holder and is suitable for mass production.

According to the method of manufacturing the connecting rod according to the second aspect of the present invention, since the connecting rod cap portion and the connecting rod body are temporarily fastened with bolts before the large end portion is divided, the dividing is performed. Since the two do not separate from each other, the connecting rod cap and connecting rod body can be securely combined,
Easy to do

According to the connecting rod manufacturing method of the third aspect of the present invention, it is possible to improve the accuracy after manufacturing.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing a first embodiment of a method for manufacturing a connecting rod of the present invention.

FIG. 2 is a vertical sectional front view of a different embodiment of the present invention.

[Explanation of symbols] C connecting rod C1 connecting rod main body C2 connecting rod cap CL large end CS small end CH bearing hole H1 connecting rod body side holder H2 connecting rod cap side cap P1 taper hole P2 taper hole T split stand B support device D lower taper pin E Upper taper pin

Claims (3)

[Claims] 1. A forging step in which a steel material cut in advance according to the size of a connecting rod to be manufactured is heated to a temperature suitable for forging to be formed into a required connecting rod shape by forging, and after the forging, this is cooled. Performing shot blasting, rough machining process that performs thickness direction, inner diameter, bolt hole processing of the large and small ends of the connecting rod, and then insert and support the holder for division supported by the die cushion method in the large end, Insert the taper pin from inside the holder from above and below and pressurize one taper pin to divide and form the connecting rod body and connecting rod cap, and then divide the connecting rod body and connecting rod cap into one piece It consists of a series of steps including a finishing process that applies finishing machining after closing, and the connecting rod body and connecting rod cap are integrally manufactured by forging. A method of manufacturing a connecting rod, which is characterized in that 2. A bolt pierced between a connecting rod cap and a connecting rod body to be divided between a roughing machining step of roughly machining a large end portion of a connecting rod formed in a forging step and a dividing step using a holder. The connecting rod manufacturing method according to claim 1, wherein a connecting bolt is inserted into the hole and temporarily tightened to prevent the connecting rod cap from being separated from the connecting rod body in the dividing step. 3. The connecting rod formed in the forging step is hot-coined or shot-blasted, cold-coined, and then rough-machined. 2. The method for producing a connecting rod according to 2.