JPH0487710A - Boring process of crank shaft of cylinder block - Google Patents

Abstract

PURPOSE:To prevent the diameter and the shape of a crank shaft hole from changing by preliminarily fastening a cylinder block main body and a bearing cap to each other, and separating the bearing cap from the cylinder block main body after preliminarily deforming a pressure welded surface of the cylinder block main body and the bearing cap. CONSTITUTION:A bearing cap 2 is assembled on a cylinder block main body 3 in a preliminary process, and both of the body 3 and the cap 2 are fastened by a bolt 5 with an axial tension of an approximate normal axial tension to each other. Thereby, the pressure welded surface of the cylinder block main body 3 and the bearing cap 2 is deformed and hardened. Thereafter, the bolt 5 is loosened and the bearing cap 2 is assembled on the cylinder block main body 3, and a crank shaft hole 1 is processed on the pressure welded surface of the cylinder block main body 3 and the bearing cap 2 as it is in the aforementioned state. Consequently, it is possible to eliminate deformation of the diameter and the shape of the crank shaft hole 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for machining a crankshaft hole in a cylinder block, and a method for removing a bearing cap.

The present invention relates to a method for machining a crankshaft hole in which the diameter of the crankshaft hole is not changed by reassembly.

[Conventional technology]

In the conventional method of machining the crankshaft hole of a cylinder block, the diameter of the crankshaft must be reproduced, so the bearing cap is assembled to the cylinder block body, and the cylinder block body and the bearing cap are assembled with the bolts tightened. A crankshaft hole is machined in the pressure contact area.

To tighten the bolts, remove the bearing cap after machining the crankshaft hole.

In order to prevent the diameter of the crankshaft hole from changing due to reassembly, the bolts were tightened with the same axial force as during normal assembly (final assembly).

[Problem to be solved by the invention]

However, in the conventional cylinder block crankshaft hole machining method, when aluminum alloy is used for the cylinder block material or the axial force of bolt tightening is strengthened compared to the conventional method, as shown in Fig. 4, Even if the bearing cap 2 is assembled to the cylinder block body, the bolts are tightened with the normal axial force (the axial force at the time of final assembly), and the crankshaft hole 1 is machined (see Fig. 4 (a)), the bearing cap is 2 is removed and reassembled, the pressure contact surface 4 between the cylinder block body 3 and the bearing cap 2 is deformed (the hatched part is the deformed part) due to the softening of the material of the cylinder block and the strengthening of the axial force of the bolt. (See FIG. 4(b)), there is a problem in that the diameter of the crankshaft hole 1 formed in the pressure contact surface 4 becomes smaller or the shape of the hole changes.

The present invention has been made by focusing on such problems of the conventional technology, and involves removing the bearing cap.

The aim is to create a crankshaft hole machining method that does not change the diameter or shape of the crankshaft hole even after repeated reassembly.

[Means for solving problems]

In order to solve the above problem, the method of machining a crankshaft hole in a cylinder block according to the present invention involves assembling a bearing cap onto a cylinder block body and tightening bolts between the cylinder block body and the bearing cap with a regular axial force. In this method, the cylinder block body and the bearing cap are pre-tightened with bolts with an axial force equal to the normal axial force before the above-mentioned assembly, whereby the cylinder block body and the bearing cap are pressed into contact with each other. It is characterized by the addition of a preliminary process of separating the bearing cap from the cylinder block body after preliminary deformation of the surface.

[Effect]

In the preliminary process, the bearing cap is assembled to the cylinder block body, and both are bolted together with an axial force that is approximately the same as the normal axial force. This deforms and hardens the pressure contact surface between the cylinder block body and the bearing cap. Next, loosen the bolts and remove the bearing cap, then re-tighten the bolts with the same axial force as during normal assembly to assemble the bearing cap to the cylinder block body, leaving the pressure contact surface of the cylinder block body and bearing cap in this state. Machining the crankshaft hole.

Since the crankshaft hole is machined using the pressure contact surface that has been hardened in the preliminary process, no matter how many times the bearing cap is removed and reassembled after the crankshaft hole is machined,
The pressure contact surface does not deform and the diameter and shape of the crankshaft hole are guaranteed.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

First, the structure of the cylinder block will be explained based on FIGS. 1 and 2. Stud bolts 5 protrude downward from the lower part of the cylinder block body 3 made of an aluminum alloy. In this embodiment, the stud bolts 5 are arranged in groups of four, and are arranged in plural sets at predetermined intervals in the direction of the crankshaft of the cylinder block body 3.

A bearing cap 2 is fitted into the lower part of the cylinder block blank body 3, and a bearing beam 6 is in contact with the lower surface of the bearing cap 2, so that the stud bolt 5 connects the bearing cap 2 and the bearing beam 6. It penetrates and protrudes downward. A nut 7 is screwed into the lower end of the stand bolt 6 to tighten the bearing cap 2 and the bearing beam 6 toward the cylinder block body 3. Further, side bolts 8 are tightened from the sides of the cylinder block body 3 toward the hair ring cap 2.

As shown in FIG. 3, the method for machining the crankshaft hole in the cylinder block having the above configuration is as follows: First, as a preliminary step, the bearing cap 2 and the bearing beam 6 are penetrated by the stud bolts 5, and the bottom of the cylinder block body 3 is drilled. After assembly, screw the nut 7 onto the lower end of the stud bolt 5, and tighten the bearing cap 2 and bearing beam 6 toward the cylinder block body 3 with the same axial force as when normally assembled (third Diagram (a)
). After a predetermined period of time in the tightened state, the pressure contact surface 4 between the cylinder block body 3 and the bearing cap 2 sinks in the tightening direction and hardens (Fig. 3).
). Next, loosen the nut 7 and remove the bearing cap 2 and bearing beam 6 from the cylinder block body 3 (see FIG. 3(C)).

Next, the bearing cap 2 is reassembled to the cylinder block body 3, and the nut 7 is screwed onto the bolt 5 with the same axial force as when normally assembled, and both 2 and 3 are tightened. Further, the bearing cap 2 and the cylinder block main body 3 are tightened from the side with the side bolts 8, and in this state, the crankshaft of the cylinder block main body 3 is attached to the pressure contact portion 4 between the cylinder block main body 3 and the bearing cap 2. The crankshaft hole 1 is machined along the direction (see FIG. 3(d)).

In the method for machining the crankshaft hole of the cylinder block of this embodiment as described above, the press contact surface 4 between the cylinder block body 3 and the bearing cap 2 is deformed in advance by carrying out the preliminary process of -degree pre-tightening. The crankshaft hole 1 is machined after machining the crankshaft hole 1 after hardening the pressure contact surface 4 so that it will not be further deformed even if the bearing cap 2 is repeatedly removed and reassembled. Even if the cap 2 is repeatedly removed and assembled, the diameter of the crankshaft hole 1 does not change.

Note that the processing method of this embodiment is not limited to the case where a soft material such as an aluminum alloy is used for the cylinder block body 3 as in the previous embodiment;
This method can be applied to cases where the pressure contact surface 4 between the cylinder block body 3 and the bearing cap 2 is deformed, such as by increasing the axial force of bolt tightening in order to strengthen the assembly between the cylinder block body 3 and the bearing cap 2.

〔Effect of the invention〕

As explained above, the method for machining a crankshaft hole in a cylinder block of the present invention involves the introduction of a preliminary process.
Since the pressure contact surface between the bearing cap and the cylinder block body is hardened in advance and the crankshaft hole is machined after that, the bearing cap must be removed several times after the crankshaft hole is machined.

Even after repeated reassembly, the pressure contact surface between the bearing cap and the cylinder block main body is not deformed, and the diameter and shape of the crankshaft hole are not deformed.

[Brief explanation of the drawing]

Figure 1 is an exploded perspective view of the cylinder block, Figure 2 is a front view of the cylinder block, Figure 3 is a diagram showing the procedure for machining the crankshaft hole, and Figure 4 is the conventional crankshaft hole contact surface. FIG. 1... Crankshaft hole, 2... Bearing cap,
3... Cylinder block body, 4... Pressure contact surface, 5...
...Bolt diagram 1

Claims (1)

[Claims] (1) In a method of machining a crankshaft hole between the cylinder block body and the bearing cap while the bearing cap is assembled to the cylinder block body and both bolts are tightened with regular axial tension, the After pre-tightening the cylinder block body and the bearing cap with bolts with an axial force of approximately the normal axial force, and thereby preliminarily deforming the pressure contact surface between the cylinder block body and the bearing cap, the bearing cap is separated from the cylinder block body. A method for machining the crankshaft hole of a cylinder block, which is characterized by the addition of a process.