JPS6351802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a processing method for drilling oil holes in a crankshaft.

[Prior Art] As is well known, a crankshaft consists of a crank journal and a crank pin eccentrically provided on the crank journal.In order to supply oil to the surface of the crank pin, oil is supplied from the surface of the crank journal to the surface of the crank pin. An oil hole must be drilled through it. This oil hole usually consists of a first oil hole that extends from the surface of the crank journal into the inside thereof, and a second oil hole that extends from the surface of the crank pin toward and communicates with the first oil hole. . Since this second oil hole passes through the crank arm that connects the crank journal and the crank pin, if its position deviates from the center of the critical cross section of the crank arm, it is unfavorable in terms of the strength of the crank arm.

On the other hand, in order to change the engine output, for example when adjusting the output range of the engine and considering creating a series of engines, a crankshaft with a different distance, or stroke, between the center line of the crank journal and the center line of the crank pin is used. be done.

Now, when drilling the oil hole, especially the second oil hole, in the crankshaft, make sure that the second oil hole is aligned with the center line of the crank pin and the crank journal so that the second oil hole passes through the center of the critical cross section of the crank arm. The angle of inclination β' with respect to the centerline of the crank journal in a plane containing the centerline (hereinafter simply referred to as the vertical plane) and with respect to the plane perpendicular to the plane containing the centerline of the crank pin and the centerline of the crank journal (hereinafter simply referred to as the horizontal plane) The inclination angle .beta. is determined, and the drill is set based on the inclination angles .beta. and .beta.' to perform drilling work.
This second oil hole work is performed from the crank pin toward the crank journal at the above-mentioned inclination angles β and β', so the holes are drilled on crankshafts whose distances between the center line of the crank journal and the center line of the crank pin are different. When the drill is to be cleared, the inclination angles β and β' must be newly determined and the drill must be set again. The position where the drill engages with the outer peripheral surface of the crankpin changes three-dimensionally depending on the change in the distance between the centers, so if the inclination angles β and β' are constant, the drill will engage the crankpin's outer circumferential surface. The oil hole is not aligned with the longitudinal center, that is, the center of the conrod metal, and the oil hole is misaligned, making it impossible to drill at the same center position of the conrod metal as the original crankshaft. This is because the flow and distribution of oil in different directions becomes uneven, resulting in inconvenience.

It is extremely troublesome to reset the drill each time a crankshaft with a different distance between the center lines of the crank journal and crank pin is machined.

[Object of the Invention] Therefore, an object of the present invention is to set a drill when drilling an oil hole from the crank pin to the crank journal on a crankshaft in which the distance between the center lines of the crank journal and the crank pin is different. To provide a method for drilling an oil hole in a longitudinal position of a crankpin without repairing it.

[Structure of the Invention] According to the present invention, in a crankshaft oil hole machining method in which an oil hole is drilled from the crank pin of the crankshaft to the crank journal, the oil hole of the crank pin of the crankshaft serving as a reference is The drill hole is determined by determining the angle of inclination β′ with respect to the center line of the crank journal in a plane including the center line of the pin and the center line of the crank journal, and the angle of inclination β with respect to the plane perpendicular to the plane including the center line of the crank pin and the crank journal. When machining an oil hole on a crankshaft where the distance between the crank pin centerline and the crank journal centerline is different from the reference crankshaft distance, it is necessary to determine the machining position and direction with respect to the crank pinni. Then move the drill or crankshaft by a certain distance △l only in the axial direction of the crankshaft, and move the drill or crankshaft to a fixed position in the same longitudinal direction as the reference crankshaft with respect to the crankpin without changing the above-mentioned inclination angles β and β'. An oil hole is drilled in the hole, and the moving distance △l is △l = (1/
tanβ′) {△r+(sinα−sinα′)(d/2)} (where △r is the difference in distance between the crank journal centerline and the crankpin centerline, d is the crankpin diameter, α and α′ The outer circumferential position of the oil hole in the right-angled cross section of the crank pin is perpendicular to the center line passing through the center of the crank journal and the center of the crank pin, and the angle formed by the center line passing through the center of the crank pin. A method for machining an oil hole in a crankshaft is provided.

[Operations and Effects of the Invention] When moved by Δl in this manner, the center lines of the first oil hole and the second oil hole do not match geometrically. However, the inner diameter of the first oil hole is about 10 mm, and the inner diameter of the second oil hole is about 6 mm, so in a normal large truck engine, for example, when changing the piston stroke from 150 mm to 140 mm, the travel distance △ l is approximately 3 to 4 mm. For that reason, the first
There is no problem because the oil hole and the second oil hole always communicate with each other.

The dangerous cross section is the cross section of the crankshaft connecting the upper end of the crankshaft and the lower end of the crank pin.
This dangerous cross section is also less than 3 to 4 mm depending on the moving distance △l (since the moving direction and the dangerous cross section are inclined,
The moving distance of the dangerous section is the cosine of Δl. )
, and there is virtually no problem. Also, as the stroke becomes smaller, the cross-sectional area of the dangerous section becomes larger, so
If the settings are made for large strokes, no problem will occur when the strokes are small. Therefore, if a change in the bore or stroke is expected, it is preferable to set in advance so that the critical cross section moves toward its center by the moving distance Δl.

Even if the center lines of the first oil hole and the second oil hole do not coincide, they cross each other at an angle, so that the opening area thereof is sufficient.

When drilling the first oil hole, the angles β and β' are set in advance as described above. It is virtually impossible to change the angles β and β' when changing the stroke, and even if it were done, it would take time to set up, making it unsuitable for mass production on a line.

However, according to the present invention, it is sufficient to simply move in the horizontal direction without changing the angles β and β', improving work efficiency.

Therefore, according to the present invention, oil holes in crankshafts of engines with different piston strokes can be easily and quickly drilled, and the oil holes can be drilled efficiently.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2. 1 and 2, the crankshaft, which is designated as a whole by the symbol C, is composed of a crank journal 1, a crank pin 2, and a crank arm 5. The crank journal 1 has a first oil hole 3a, and the crank journal 1, crank arm 5, and crank pin 2 have a second oil hole 3b that straddles them and communicates with the first oil hole 3a. A hole is drilled through the center. The second oil hole 3b is designed in consideration of the bearing load, oil pressure distribution, oil film distribution, etc. when the distance between the center lines between the crankshaft 1 and the crank pin 2 is R and the diameter of the crank pin is d. It is determined at the optimal position in the longitudinal direction, and the center line O of the crank journal and the center line of the crank pin
The inclination angle β' with respect to the centerline O of the crank journal in a plane containing O' (vertical plane) and the inclination angle β with a plane perpendicular to the vertical plane (horizontal plane), that is, a horizontal plane including the centerline O of the crank journal, are determined. ing.

Therefore, the reference crankshaft C, in which the diameter of the crank pin 2 is d and the distance between the crank pin 2 and the crank journal 1 is R, is drilled with a drill set at the above-mentioned inclination angles β' and β. The oil hole 3b is drilled.

Next, a method of machining the second oil hole 3b' of a crankshaft different from the reference crankshaft in which the distance between the crank journal 1 and the crank pin 2 has changed from R to r will be described. In this case, if the axis of the drill is not changed in order to improve the work efficiency of drilling, the oil hole will be marked 3b in Figure 1.
It will be formed at the position shown in . That is, as can be seen from FIGS. 1 and 2, when the distance between the center lines is R, the tip of the drill engages with the crank pin 2 at point A, but when the distance between the center lines becomes r, Since r<R, the position where the tip of the drill engages with the surface of the crank pin 2' is the position indicated by A'. Therefore, when the second oil hole is drilled in this manner, the oil hole position A' is shifted by Δl from the optimum position, that is, the center of the conrod metal, which is not preferable for the formation of an oil film. Therefore, the drill unit is shifted by Δl in the longitudinal direction of the crown axis so that the position where the tip of the drill engages with the surface of the crank pin 2' is A''.

Normally, the drill unit is configured to be movable in the axial direction of the crankshaft, so the above-mentioned travel distance △
By storing l in advance in the numerical control device, even if the distance between the crank journal and crank pin changes, the drill unit can be moved in the longitudinal direction of the crankshaft without having to reset the inclination angles β and β' of the drill unit. Drilling work can be easily performed by simply moving the machine.

Therefore, the present invention aims to provide a method of moving a drill unit in a fixed direction to form an oil hole at a predetermined optimum position. That is, when the drill is moved to the right by △l as shown in Fig. 1, the biting point of the drill against the crank pins 2 and 2' moves from A to A'', and the oil hole is formed at the optimal position. If the amount of change in the stroke of the crank pin, that is, the distance between the crank journal and the crank pin, is determined, then this △l can be determined using the following formula. The angle between the line connecting the biting point A and the axis O' of the crank pin 2 and the line X-X is α, and the changed drill biting point A' of the crank pin 2' and the axis center of the crank pin 2' is α. If α' is the angle that the line connecting O'' makes with X'-X', then ''=(d/2) sin
/
2) sinα′, that is, ″=△r(sinα−sinα′
)
(d/2) (however, △r=R−r, and d is the diameter of the crank pin), therefore, △l when the drill unit is moved by △l is △l= (″/tanβ′)=(1/tanβ′)
{△
r+(sinα−sinα′)(2/d)}. Therefore, the distance between the crank journal and the crank pin is R, and the diameter of the crank pin is d.
If the drill is set to form an oil hole on the reference crankshaft with inclination angles β' and β, then when the distance between the shafts becomes r to change the stroke, the above formula can be used. The obtained △l
By moving the drill to the right in Fig. 1, it is possible to drill the oil hole 3b' where the biting point of the drill is A''.

In addition, although the example of moving the drill has been explained above, since the drill and the workpiece, that is, the crankshaft, are in a relative positional relationship, instead of moving the drill, the crankshaft should be moved axially by △l to the left in Figure 1. It is clear that the oil hole 3b' can also be formed by moving it. Also, if the distance between the shafts becomes larger than the reference crankshaft distance in order to increase the stroke, the drill must be moved to the left in Figure 1 by △l, or the crankshaft must be moved to the right. It is also clear that this is not the case.

[Summary] As explained above, according to the present invention, by moving the oil hole forming drill for lubricating oil in the axial direction of the crankshaft, it is possible to move the drill from the crank pin of a crank with a different stroke to the crank journal without resetting the drill. It is possible to process oil holes up to . Therefore, oil holes can be easily drilled, and series production based on engine output can be achieved at low cost.

[Brief explanation of drawings]

The drawings are diagrams for explaining the method of drilling an oil hole in a crank according to the present invention, in which FIG. 1 is a front view of the crank, and FIG. 2 is a schematic diagram seen in the direction of the arrow - in FIG. 1. be. 1...Crankshaft, 2...Crank pin, 3
b, 3b'...Oil hole, β, β'...Oil hole inclination angle,
△l...Amount of movement of the drill or crankshaft.

Claims (1)

[Claims] 1. In the method of machining the first oil hole of the crankshaft in which a second oil hole is drilled from the crank pin of the crankshaft to the crank journal, the first oil hole of the crank pin of the crankshaft serving as a reference is the first oil hole of the crank shaft. The crank angle of the drill hole is determined by determining the inclination angle β' with respect to the center line of the crank journal in a plane including the center line and the center line of the crank journal, and the inclination angle β with respect to a plane perpendicular to the plane including the center line of the crank pin and the crank journal. The machining position and direction for the pin are determined, and the second crankshaft is placed on the crankshaft, which is different from the distance between the crankpin centerline and the crank journal centerline.
When machining an oil hole, a certain distance △l is created only in the axial direction of the crankshaft due to the difference in the center line spacing.
drilling a second oil hole at substantially the same longitudinal position as the reference crankshaft with respect to the crankpin without changing the inclination angles β and β′ by moving the drill or the crankshaft; The fixed distance △l it moves is △l=(1/tanβ′){△r+
(SINα−sinα′)(d/2)} (where △r is the difference in distance between the crank journal centerline and the crankpin centerline, d is the crankpin diameter, and α and α′ are the distances between the crankpin centerline and the crankpin centerline, respectively. A crankshaft characterized in that the outer circumferential position of the oil hole in a right-angled cross section is set at an angle (at right angles to a center line passing through the center of the crank journal and the center of the crank pin) and at an angle made with a center line passing through the center of the crank pin. How to process oil holes.