JP2000158344A - Machine part processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanical part having good smoothness, capable of forming a desired processed shape, and having excellent durability, and having excellent workability and environmental friendliness. A method for processing mechanical parts is provided. SOLUTION: The nozzle 1 is changed from B → B ′ → C ′ → C, and D
Ultra high-pressure water (100-400MP) mixed with abrasive grains while moving along the desired R shape in the order of → D ′ → E ′ → E
a) is injected into the corners 16 and 17 of the cylindrical roller 11. As a result, the corners 16 and 17 are formed in a desired round shape, and the corners 16 and 17 and the end surfaces 31 and 32 and the rolling surface 18
Are connected in a common tangent manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for machining a machine part, and more particularly to a method for machining a machine part such as a cylindrical roller in a rolling bearing with improved shape accuracy.

[0002]

2. Description of the Related Art In general, a cylindrical roller as a mechanical part incorporated in a rolling bearing is formed in a round shape with rounded corners.

For example, in a NU type cylindrical roller bearing,
As shown in FIG. 10, a cylindrical roller 53 is loosely fitted between an outer ring flange 51 and an inner ring flange 52 so as to freely roll.

In the NU type cylindrical roller bearing, FIG.
As shown in the figure, a corner 53a of a cylindrical roller 53 which is a rolling element
Are formed in an R shape, and the cylindrical roller 53 rolls while the rolling surface of the cylindrical roller 53 and the end surface of the outer ring flange 51 which is the raceway slide.

Conventionally, the corners 53a of the cylindrical rollers 53 are formed by forging or cutting.
Since it is necessary to connect the connection points a and b between the corner 53a and the rolling surface 53b and the end surface 53c shown in FIG. 12 smoothly, that is, with a small R dimension, it is further processed by the following method.

(1) A cylindrical roller 53 to be processed is mixed with a medium mainly composed of abrasive grains, water, and the like, placed in a container called a barrel, and the barrel is rotated to mechanically grind a mechanical part. Barrel processing method (2) Liquid honing method in which abrasive grains and working fluid are sprayed onto the surface of cylindrical rollers 53 with compressed air (3) Grinding processing to grind cylindrical rollers 53 with fixed abrasive grains such as abrasive cloth or elastic grindstone The connection points a and b of the cylindrical roller 53 are formed in an R shape by using a method such as a method.

[0007]

However, of the above-mentioned conventional machining methods for mechanical parts, the barrel machining method forms the connection points a and b into an R shape by the so-called stirring effect of the free abrasive grains and the cylindrical rollers 53. Therefore, although it is suitable for mass production, it is difficult to form a desired R shape due to unstable processing amount.
There is a problem that a dent is likely to be formed on the cylindrical roller 53 due to collision between the cylindrical rollers 53.

Further, in the barrel processing method, even when the connection points a and b are processed into an R shape by the stirring effect, as shown in FIG. It is difficult to connect the rolling surface 53b or the end surface 53c of the second tangent line tangentially. When the connection is imperfect as described above, stress is concentrated on the connection points a and b when the cylindrical roller 53 is incorporated into the rolling bearing and operated, and the fatigue life of the cylindrical roller 53 as a mechanical part is reduced. There was a problem that it decreased.

In addition, the barrel processing method comprises a cylindrical roller 5
3 is put into a barrel together with a medium or the like and subjected to the processing, so that there is a problem that workability is poor in the work of removing the cylindrical roller 53 after the processing and the working environment is also bad.

In addition, since the liquid honing method uses compressed air, the medium ejected from the nozzle diffuses and scatters, and therefore, when performing local processing such as the corner 53a, there is a limit in processing accuracy. There is also a problem that the working environment is poor.

Further, since the grinding method is a method in which fixed abrasive grains are elastically pressed against the cylindrical rollers 53, if clogging or abrasive grains fall off, a variation in the amount of grinding occurs, and a desired round shape is obtained. There was a problem that it became impossible. In addition, since the fixed abrasive grains are elastically pressed against the cylindrical roller 53, the R-shaped corner 53a and the rolling surface 53b or the end surface 53c of the cylindrical roller 53 are formed in the same manner as in the barrel processing method.
It is difficult to connect them in a common tangential manner, and thus the connection points a and b are incompletely connected, stress is concentrated, and the fatigue life of the cylindrical roller 53 is reduced.

Further, other mechanical parts other than the cylindrical rollers,
For example, in a plate-like member processed by a milling machine or the like, similarly, an edge is generated at a connection point between the processed portions and stress is concentrated on the edge portion, and the life of the mechanical component is shortened. There was a point. Also, in the case of a ball receiving portion of an axial hydraulic pump, the so-called rounding of the edge is similarly important.

The present invention has been made in view of the above problems, and can provide a machine part having good smoothness, capable of forming a desired processed shape, and having excellent durability. Further, it is an object of the present invention to provide a method of processing a machine part which is excellent in workability and environmental performance.

[0014]

In order to achieve the above object, the present invention provides a method for processing a mechanical part, comprising: jetting a liquid containing abrasive grains from a nozzle to a predetermined portion of the mechanical part at a predetermined high pressure; It is characterized in that a predetermined portion is processed.

According to the above method, since the liquid mixed with the abrasive grains is jetted from the nozzle to the predetermined portion of the mechanical component at a predetermined high pressure, a large amount of energy is concentrated at the predetermined portion. Then, the liquid ejected from the nozzle at a predetermined high pressure does not diffuse but forms a layer, and the liquid flows in a shape following the shape of the machine component. Therefore, by moving the nozzle or the mechanical part so that the predetermined part of the mechanical part has a desired processing shape, the predetermined part can be processed into a desired shape. In this case, among the predetermined parts of the mechanical part, the non-smooth part (non-smooth part) has a higher resistance than the smooth part due to the collision of the abrasive grains, so that the non-smooth part is selectively ground than the smooth part. You. Accordingly, the predetermined portion has a smooth surface shape connected in a common tangent manner without leaving a non-smooth portion.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view of a nozzle used in a method for processing a machine part according to the present invention.
A water nozzle 2 having an orifice 40 at the tip through which ultrahigh-pressure water of 100 to 400 MPa passes;
Abrasive nozzle 3 for injecting ultra-high pressure water mixed with abrasive grains from a tapered tip having a diameter of 5φ to 1.0φ
And an adapter 4 externally fitted to the water nozzle 2
And the water nozzle 2 and the abrasive nozzle 3
A nozzle body 6 accommodating the adapter 4 and having an abrasive inlet 5; a collet 10 for fixing the nozzle body 6; a nozzle holder 7 fixed to the abrasive nozzle 3; A first flow control valve 8 for controlling the introduction of the abrasive grains to the nozzle body 6 and a second flow control valve 9 for controlling the introduction of the abrasive grains to the nozzle body 6.

In the nozzle 1, a first flow control valve 8 is connected to a jet pump (not shown). Ultra high pressure water from the jet pump is supplied to the water nozzle 2 and a second flow control valve 8 is provided. The control valve 9 is connected to an abrasive tank (not shown), and the abrasive from the abrasive tank is supplied to the abrasive nozzle 3 through the abrasive inlet 5. And
Water mixed with abrasive grains is sprayed from the abrasive nozzle 3 to a predetermined portion of a machine part as a workpiece at a high pressure of 100 to 400 MPa (predetermined high pressure).

Although not shown, the nozzle 1 is mounted on a ball-integrated linear motion guide surface assembled on the XY orthogonal axis in the Z-axis direction (vertical direction) with respect to the XY orthogonal axis via a jig. ing. The nozzle 1 is driven by an AC servomotor (not shown), and the speed of the AC servomotor is controlled by a voltage output from a control computer (not shown). Further, an encoder is mounted on the AC servomotor, and the encoder detects the position of the nozzle 1 and supplies an output signal thereof to the control computer.

As shown in FIG. 2, the jet flow of the nozzle 1 is divided into a jet acceleration region R1, a droplet flow region R2, and a diffusion region R3.

The jet acceleration region R1 is, as shown in FIG.
Hydrodynamically, it is a continuous flow having a constant dynamic pressure. That is, in the jet acceleration region R1, a continuous flow having the dynamic pressure Pdyn as shown by the equation (1) is generated, and no large energy for deforming the workpiece is generated.

[0022] ^{Pdyn = ρ · v 2/2} ... (1) where, ρ is the density of the water, v is the flow rate.

In the droplet flow region R2, as shown in FIG. 4, an impact pressure Pimp which is much larger than the dynamic pressure Pdyn in the jet acceleration region R1 is generated. That is, in the small droplet flow region R2, an impact pressure Pimp as shown by the equation (2) is generated, and a large energy for deforming the workpiece, that is, a water droplet having an impact force is generated.

Pimp = k · μ · ρ · c · v (2) where k is a constant, μ is the viscosity of water, and c is the speed of sound.

Then, as described above, in the droplet flow region R2, the impact pressure Pimp is generated, and a water droplet having an impact force is generated. A compressive residual stress can be provided. For example, when water is sprayed to a predetermined portion at a high pressure of 100 mPa for 15 seconds, a residual compressive stress of 800 mPa can be applied to the surface layer.

The diffusion region R3 is a region where a water jet is generated by diffusion of the jet.

Therefore, by disposing the mechanical component in the droplet flow region R2 where the impact pressure Pimp is generated, and spraying ultra-high pressure water containing abrasive grains to a predetermined portion of the mechanical component, a large amount of energy is concentrated on the predetermined portion. . Then, the ultrahigh-pressure water jetted from the nozzle 1 flows in a form that follows the shape of the mechanical part. Therefore, by appropriately moving the nozzle or the mechanical part so that the predetermined part of the mechanical part has a desired processing shape, the predetermined part can be processed into a desired shape. In this case, among the predetermined portions of the mechanical component, the non-smooth portion has a higher resistance than the smooth portion due to the collision of the abrasive grains, so that the non-smooth portion is more selectively ground than the smooth portion. Therefore, the predetermined portion has a smooth surface shape connected tangentially without any non-smooth portion remaining, whereby stress is not concentrated on a specific portion of the predetermined portion, and the durability of the mechanical component is improved. be able to.

Further, mechanical parts are arranged in the droplet flow region R2 of the nozzle 1 and the abrasive grains are shut off, and only water is supplied to the nozzle 1
When jetted to the mechanical component at an ultra-high pressure from above, it is possible to apply compressive residual stress to the mechanical component in a short time due to the collision of high frequency and dynamic water droplets, thereby improving the fatigue life. .

Next, the embodiment of the present invention will be described in more detail by taking a cylindrical roller of a rolling bearing as an example of a mechanical part.

FIG. 5A is a view showing a processing procedure of a method for processing a cylindrical roller, and FIG. 5B is a view taken along the line XX of FIG. 5A.

A first center 14 and a second center 15 each having a conical tip are inserted into the cylindrical portion of the cylindrical roller 11 to connect the first and second centers 14 and 15 with the cylindrical roller 11. At the same time, the first center 14 is driven to rotate in a direction indicated by an arrow P via a drive motor (not shown), and the second center 15 is driven to rotate. Rotate.

When a residual compressive stress is to be applied to the cylindrical roller 11, the cylindrical roller 11 is first arranged in the droplet flow region R2 where the impact pressure Pimp is generated from the nozzle 1 (the position of the cylindrical roller 11 is as described above). Detected by an encoder not shown). Next, while closing the second flow control valve 9 to cut off the supply of the abrasive grains to the nozzle 1, the first flow control valve 8 is opened, and the nozzle is rotated while rotating the cylindrical roller 11 in the direction of arrow P. 1 is appropriately swirled, and only the ultra-high pressure water from the jet pump is jetted from the nozzle 1 to the cylindrical roller 11 to perform a water peening treatment on the cylindrical roller 11.

That is, as shown in FIG. 5A, the nozzle 1 is arranged at a position A at an angle θ with respect to the axis of the cylindrical roller 11 so that the nozzle 1 does not interfere with the second center 15. Is injected to the end position G of the recess 13. Then, the nozzle 1 is moved to a position B corresponding to a position H, which is a connection point between the end face 31 and the corner 16, while injecting ultra-high pressure water from the nozzle 1. Thereby, the end face 3
A residual compressive stress is applied to the surface layer 1 (between the position G and the position H). Next, the nozzle 1 is moved to a position C corresponding to a position I which is a connection point between the corner 16 and the rolling surface 18, and the ultrahigh-pressure water is jetted toward the position I. And then
The nozzle 1 is moved to a position D corresponding to a position J which is a connection point between the corner 17 and the rolling surface 18 while injecting ultra-high pressure water from the nozzle 1. As a result, a residual compressive stress is applied to the surface layer of the rolling surface 18 (between the position I and the position J).
Next, the nozzle 1 is moved to a position E corresponding to a position K which is a connection point between the corner 17 and the end face 32, and the ultrahigh-pressure water is jetted toward the position K. Thereafter, the nozzle 1 is moved to a position F corresponding to the end position L of the concave portion 12 while injecting the ultra-high pressure water from the nozzle 1. Thereby, the end face 32
A residual compressive stress is applied to the surface layer (between the position K and the position L).

As described above, the nozzle 1 is moved from A → B, C → D,
By sequentially moving from E to F, a residual compressive stress can be applied to the surface layers (20 μm below the surface) of the end surfaces 31 and 32 and the rolling surface 18, and the fatigue life of the cylindrical roller 11 can be improved. .

The corners 16 and 17 of the cylindrical roller 11 are
When processing into a shape, first, the cylindrical roller 11 is
After that, the first and second flow control valves 8 and 9 are both opened, and the ultra-high pressure water mixed with abrasive grains is sprayed onto the corners 16.

That is, as shown in FIG. 5A, after the nozzle 1 is arranged at the position B corresponding to the position H of the cylindrical roller 11, the nozzle 1 is moved to the cylindrical roller 1 as shown in FIG.
1 is turned to the position B 'on the position H, and the processing surface of the corner portion 16 is ground from the lateral direction by loose abrasive grains. Next, as shown in FIG. 5B, the nozzle 1 is moved from the position B 'to the position C' along a desired R shape, and grinding is performed using loose abrasive grains. Thereby, the corner 16 is ground into a desired round shape.

Similarly, as shown in FIGS. 5A and 5B,
After arranging the nozzle 1 at the position D corresponding to the position J of the cylindrical roller 11, the nozzle 1 is turned from the position D to the position D ', and then the nozzle 1 is moved from the position D' along the desired R shape. The corner 17 is moved to the position E ', and the processing surface of the corner 17 is ground from the lateral direction with loose abrasive grains to grind the corner 17 into a desired R shape. Thereafter, the nozzle 1 is turned from the position E 'to the position E, and the machining of the corner portion 17 is completed.

As described above, in the present embodiment, the corners 16,
17 is processed into a desired round shape along the hydrodynamic flow. In this case, the non-smooth portion of the corners 16 and 17 has a higher resistance than the smooth portion due to the collision of the abrasive grains, and is thus selectively ground than the smooth portion. Therefore, even at positions G to K which are connection points between the corners 16 and 17 and the end surfaces 31 and 32 or the rolling surfaces 18, non-smooth portions do not remain, and a smooth surface shape connected in a common tangent manner is obtained. It is possible to avoid the occurrence of stress concentration and improve the fatigue life. Further, since the cylindrical rollers 11 are processed one by one, the cylindrical rollers 1 are processed as in the barrel processing method.
No dents or the like occur due to collisions between the 1s. Moreover,
Since the water is sprayed using the nozzle, the amount of water used each time is small (the spray pressure is 100 to 400 MPa, the nozzle 1
Of 1 mm in diameter and the water volume is 2 l / min or less), and is excellent in workability and environmental friendliness.

In the above embodiment, after the cylindrical roller 11 is subjected to quenching and tempering, the corners 16 and 17 are first processed by free abrasive grains with ultra-high pressure water mixed with abrasive grains. After that, the end faces 31, 32 and the rolling face 18 of the cylindrical roller 11 are subjected to the water peening process, so that the above-described processing can be continuously performed with the minimum flow line.

Specifically, with the second flow control valve 9 closed, the position of the nozzle 1 is moved from A to B, peening is performed only with ultra-high pressure water, and residual compressive stress is applied to the end face 31. After that, the second flow control valve 9 is opened, and the position of the nozzle 1 is sequentially moved from B → B ′ → C ′ → C to perform grinding of the corner 16 using loose abrasive grains. At the same time, the corner 16 and the end surface 31 or the rolling surface 18 are connected in a common tangential manner. Next, the second flow control valve 9 is closed again, the position of the nozzle 1 is moved from C to D, peening is performed only with ultra-high pressure water, residual compressive stress is applied to the end face 31, and then the second flow control is performed again. 2 is opened, the position of the nozzle 1 is sequentially moved from D → D ′ → E ′ → E, and the corner 16 using the free abrasive grains is ground to form the desired corner 17. At the same time, the corner 17 and the end face 32 or the rolling face 18 are connected in a common tangential manner. Finally, the second flow control valve 9 is closed, the position of the nozzle 1 is moved from E to F, peening is performed only with ultra-high pressure water, residual compressive stress is applied to the end face 31, and the cylindrical roller 11 is rotated. Finish the processing. Thus, continuous processing can be performed with a minimum flow line.

In the above embodiment, the nozzle 1 is moved to perform the rounding of the corners 16 and 17 with the loose abrasive grains and the water peening of the end surfaces 31 and 32 and the rolling surface 18. The above-described R processing and water peening may be performed by fixing the nozzle 1 and holding the cylindrical roller 11 with a robot hand, and moving the cylindrical roller 11 relative to the nozzle 1.

In the above-described embodiment, the loose abrasive processing is performed in the small droplet flow region R2 of the nozzle 1, but may be performed in the diffusion region where a water jet is generated.

FIG. 6 is a view showing a second embodiment of the method of processing a mechanical part according to the present invention. In the second embodiment, a cylindrical roller 11 as a mechanical part is fixed by a magnet chuck 19. The magnet chuck 19 is fixed by suction.
Is rotated in the direction of arrow Q so as to be pressed against the shoe 20, while the nozzle 1 is swung and swung so as to follow the processing shape.

That is, in the second embodiment, the nozzle 1 is moved at a predetermined angle {0} and a predetermined angle {
1 between the corner 16 and the rolling surface 1.
8 is formed smoothly. Similarly, the nozzle 1 is swung between a predetermined angle ψ′0 and a predetermined angle ψ′1 while spraying ultra-high-pressure water mixed with abrasive grains from the nozzle 1 onto the line at the position H, so that the angle The position H connecting the part 16 and the end face 31 is formed smoothly.

The other corner 17 is also turned over by turning the cylindrical roller 11 upside down and fixing the concave portion 13 side by suction with a magnet chuck 19, thereby similarly smoothing the corner 17 and the rolling surface 31 or the end surface 32. Can be connected to

FIG. 7A is a view showing a third embodiment of the method for processing a mechanical part according to the present invention, and FIG. 7B is a sectional view taken along the line YY of FIG. 7A. is there.

In the third embodiment, a substantially L-shaped guide plate 30 is provided in the jet acceleration region R1 of the nozzle 1, the jet direction is changed by the guide plate 30, and the jet cross section is formed in an R shape. The corner 16 of the cylindrical roller 11 is arranged in the droplet flow region R2 of the nozzle 1. That is, in the jet acceleration region R1 exhibiting a continuous flow, the jet collides with the guide plate 30 to change the flow direction of the jet, and water containing abrasive grains is jetted to the corner 16 of the cylindrical roller 11 in the droplet flow region R2. Thus, the corner portion 16 is processed into a desired R shape without an edge at the connection points M and N.

FIG. 8 is a view showing a fourth embodiment of the method for processing a mechanical component according to the present invention. In the case where the upper surface 22 of the plate-like member 21 as the mechanical component is planar-processed by a milling machine, The projections 23 and 24 having a very small height may remain between the processing eyes and the processing eyes, but the ultra-high-pressure water mixed with abrasive grains is sprayed from the nozzle 1 to the projections 23 and 24 to form the projections. 23 and 24 are removed.

FIG. 9 is a view showing a fifth embodiment of the method of machining a mechanical part according to the present invention, wherein a concave ball receiving surface 26 and a linear ball receiving surface 26 like a ball receiver 25 of an axial hydraulic pump are shown. When an edge occurs at the connecting portion 28 with the portion 27, the connecting portion 28 can be processed into an R-shape by injecting the nozzle 1 with the ultrahigh-pressure water mixed with abrasive grains to the connecting portion 28. .

[0050]

As described above in detail, in the method of processing a mechanical part according to the present invention, the liquid containing abrasive grains is jetted from a nozzle to a predetermined part of the mechanical part at a predetermined high pressure. The portion can be machined into a desired shape, and the non-smooth portion of the predetermined portion of the machine component is selectively ground more than the smooth portion by the loose abrasive grains. It is possible to avoid the non-smooth portion from remaining, thereby preventing concentration of stress at a specific portion of a predetermined portion, and obtaining a mechanical part having excellent durability.

Further, since a predetermined portion is processed by injecting a liquid from the nozzle, the amount of the liquid used can be reduced, and a desired machine part can be manufactured under a condition excellent in workability and environment. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a nozzle used in a method for processing a machine component according to the present invention.

FIG. 2 is a diagram for explaining a jet structure of a nozzle.

FIG. 3 is a graph showing a relationship between time and pressure in a jet acceleration region.

FIG. 4 is a graph showing a relationship between time and pressure in a droplet flow region.

FIG. 5 is a view showing one embodiment (first embodiment) of a method for processing a mechanical part according to the present invention.

FIG. 6 is a view showing a second embodiment of the method for processing a mechanical part according to the present invention.

FIG. 7 is a view showing a third embodiment of the method for processing a mechanical part according to the present invention.

FIG. 8 is a view showing a fourth embodiment of the method for processing a mechanical part according to the present invention.

FIG. 9 is a view showing a fifth embodiment of the method for processing a mechanical part according to the present invention.

FIG. 10 is an external view showing an example of a cylindrical roller bearing.

FIG. 11 is an enlarged view of a portion S in FIG. 10;

FIG. 12 is an enlarged view of a main part of a cylindrical roller.

[Description of Signs] 1 Nozzle 11 Cylindrical roller (machine part) 21 Flat plate member (machine part) 25 Ball receiver (machine part)

Claims (1)

[Claims] 1. A method for processing a mechanical part, comprising: jetting a liquid containing abrasive grains from a nozzle to a predetermined part of the mechanical part at a predetermined high pressure to process the predetermined part.