JPS59113313A - Crankshaft - Google Patents

Abstract

PURPOSE:To efficiently perform balance corrective operation by forming balance parts on the outer periphery of webs composing a counterweight and further forming balance corrective faces in the balance parts and then cutting in said balance corrective faces while rotating a crankshaft. CONSTITUTION:A crankshaft is equipped with webs 11-18 composing a counterweight and crank pins 21-24 to which con rods of a piston are connected. In this case, a balance part 25, projecting in the diametric direction at a predetermined circumferential position, is formed in one body with the outer periphery of each web 11-18. Further, balance corrective faces 27 cut in concentrically to an axis of rotation 26 are formed on the outer periphery of the balance parts 25. Correction of balance of the crankshaft is performed through putting said shaft in rotation while supporting it with journal parts 29 at its both ends, and further cutting in the balance corrective faces 27 while calculating the quantity of unbalance on balancing faces L and R.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates primarily to a crankshaft used in a reciprocating engine.

Generally, inertia force based on the reciprocating motion of the piston and inertia force due to the rotating mass act on this type of crankshaft.
These factors cause vibrations, so a counterweight is provided to cancel out the inertial force.This counterweight is integrally formed with the crankshaft, and is designed to suppress the vibrations as much as possible during the crankshaft machining process. Balance will be corrected.

Conventionally, the balance of the counterweight has been corrected by drilling holes 2 in the outer circumferential surface 11L of the web 1 constituting the counterweight and reducing the mass of this part, as shown in Fig. 1. [, Japanese Unexamined Patent Application Publication No. 1983-
(See Publication No. 65854).

This is because drilling with a drill is a simple process and can be easily automated or semi-automated, but on the other hand, it has the following drawbacks.

(b) When correcting the balance, measure the amount of unbalance by rotating the crankshaft with a balance measuring machine, then stop the rotation of the crankshaft, drill a hole, and then use the balance measuring machine again. It is necessary to repeatedly measure the amount of unbalance while rotating the crankshaft, which is cumbersome. Also, it takes time to measure and double the data. However, in the case of mass production, multiple measuring machines and correction machines are required, resulting in high costs.

(b) The diameter of the drill is limited to one smaller than the thickness of the web, and even if the hole is deepened, the mass of the center of the web will only decrease, resulting in a large inertia moment of the web.
<Since it does not change, the amount of balance correction cannot be made large.

(c) When drilling holes with a drill, when the process is automated, a component force method is generally used that fixes one correction angle position, and the initial unbalance amount and the correction allowable value that can be corrected with one drilling are generally used. Due to the relationship, primary and secondary corrections are necessary. Also, 1
Next, the secondary correction requires drilling at different predetermined positions in the circumferential direction, and on the other hand, the circumferential area in which holes can be drilled is limited, so in practice, the number of drill holes 2 is about 6. This limits the amount of balance correction that can be made from this point of view. Therefore, a mass centering process, which will be described later, is required, which increases the number of man-hours, and also requires expensive mass centering fees, resulting in high costs.

This invention has been made to solve the above-mentioned conventional drawbacks, and includes forming a balance portion that protrudes in the radial direction at a predetermined circumferential position on the outer periphery of a web constituting a counterweight. , with a configuration in which a balance repair surface is carved concentrically with the rotation axis of the crankshaft, the balance is corrected by cutting the above correction surface while rotating the crankshaft. The purpose is to provide a crankshaft that improves efficiency and allows for a large amount of balance correction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows a crankshaft of a four-cylinder engine, which has webs 11-18 constituting a counterweight and crank bins 21-24 to which piston connecting rods (not shown) are connected.

A balance portion 25 is integrally formed on the outer periphery of each of the webs 11 to 18 and protrudes in the radial direction at a predetermined circumferential position. For example, as shown in FIGS. When the angle is taken counterclockwise around the rotation axis 26 with the 0 o'clock position as 06, the web 11.18
For the web 12.17, the balance portion 25 is integrally formed at a circumferential position of 2706° to 660°;
″~180″, 180″~ for web 14.15
A balance portion 25 is integrally formed at each circumferential position of 270'.

Further, a balance correction surface 27 is formed on the outer periphery of the balance portion 25 and is cut concentrically with the rotation axis 26 . Note that FIGS. 6) to 6(D) are side views seen from the direction of the arrow (■) in FIG.

Next, an example of a method for correcting the balance of the crankshaft configured as described above will be described.

First, the crankshaft shown in Fig. 2 is supported by the journal parts 29 and 29 at both ends and rotated, the unbalanced phase and amplitude are detected by a pickup, and based on these detected values, the crankshaft is balanced. Calculate the amount of imbalance at . The above-mentioned balancing surface R can be set to an arbitrary value.

The amount of unbalance on the above balancing surface is shown in Figure 6 (
A) Size and angle (rotational position) indicated by UL
If the above U is the component forces UL and VL.

The component force UL,v is removed by cutting the balance correction surface 27 of the balance section 25 of the web 11, and the component force UL,H is divided into the web 1 of FIG. 6(B).
, 2 are removed by cutting the balance correction surfaces 27. The above-mentioned cutting is performed by cutting the balance correction surface with a cutting tool while rotating the crankshaft.

Furthermore, when the unbalance amount has the magnitude and angle shown by UL2 in FIG. 6(A), the component force UL, V
", the balance correction surface 27 of the web 13 in FIG. 3 (o) is removed by cutting, and the component forces UI and tH are removed by cutting the balance correction surface 27 of the web 14 in FIG. 6 (D). .

Correction of the amount of unbalance on the balancing plane R in Figure 2 [E
is also done in a similar manner.

In this way, the balance is corrected by cutting the balance correction surface 27 shown in Fig. 6 while rotating the crankshaft. The more corrections can be made, the faster and easier the balance correction work will be.

In addition, both unbalance measurement and balance correction are performed while rotating the crankshaft, so when an unbalance measuring machine and a balance correcting machine are integrated into one machine, this machine becomes more compact. Become.

Furthermore, since the balance correction surface 27 to be cut is formed on the balance part 25 that protrudes in the radial direction, the distance from the rotation axis 26, that is, the moment arm is large, so that the balance correction surface 27 can be balanced with a small cut depth. A large amount of correction can be made. Therefore, even if the crankshaft has a large amount of imbalance, it is possible to sufficiently correct the balance.

Actually, in the conventional example shown in Fig. 1, an iron web 1 with a specific gravity of 7.85 is used, its thickness is 1011, the radius of curvature a is 60 m,
The diameter and depth of the five direction holes 2 are respectively 8 m and 25-
In this case, the amount of balance correction is only about 1392·α, whereas the thickness of the web 11 shown in FIG.
Similarly, when set to 60111+ - balance correction surface 27
By cutting down by 2.5m, the amount of balance correction reaches 2042.

In addition, in the conventional crankshaft manufacturing process, before rough machining of bottles and journals using a lathe or milling, the balance is measured in the state of the material and a machining reference hole is drilled in the balance center, which is called mass centering. At the time of final balance correction, the correction i'Ejf was minimized as much as possible, but this increased the number of man-hours due to mass centering and generally the mass centering M10 was expensive, resulting in high costs. However, in this invention,
Since a lathe can be used as a balance correction machine, this balance correction machine can also perform the rough machining described above, and as mentioned above.
By integrating the balance correction machine and balance measurement machine, the rough machining and balance correction described above can be performed simultaneously while measuring the balance.
It can also be carried out in one step, and the mass centering step can be omitted, further improving work efficiency.

In the above embodiment, one balance part 25 was formed in each of the webs 11 to 18, but as shown in FIGS. 4 and 5, one web 19 has two balance parts 25 at different positions in the circumferential direction. 25 may be formed, and in this case, the number of webs is small, such as in a 5-cylinder engine with a single cylinder or a 2-cylinder engine, or when it is desired to provide a balance section only on some of the webs in a 6-cylinder or 4-cylinder engine. It is advantageous for such things.

As explained above, according to the present invention, a radially protruding -t balance part is formed on the outer periphery of the web at a predetermined circumferential position, and a Since a balance correction surface is formed, the balance correction is performed by cutting the balance correction surface while rotating the crankshaft, so the balance correction described above can be performed while continuing the balance measurement. This makes balance correction work faster and easier. Furthermore, since the moment arm of the balance correction surface is large, there is an advantage that the amount of balance correction can be increased.

[Brief explanation of the drawing]

Fig. 1 is a side view of a web showing a conventional example, Fig. 2 is a front view showing an embodiment of the present invention, and Figs. FIG. 4 is a side view of a web showing another embodiment of the present invention. FIG. 5 is a front view seen from the right side of FIG.・Balance part, 26
...Rotation axis center, 27...Balance correction surface. Figure 3 (C) 18♂ Figure 4 (D) Figure 5

Claims (1)

[Claims] (1) A balance part is formed on the outer periphery of the web constituting the counterweight and protrudes in the radial direction at a predetermined circumferential position, and this balance part is machined concentrically with the rotation axis of the crankshaft for balance correction. A crankshaft characterized by having a surface formed thereon.