JP3744082B2 - Dynamic pressure generating groove machining method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dynamic pressure generating groove machining method for a hydrodynamic bearing having a shaft and a sleeve and having a dynamic pressure generating groove on a bearing inner peripheral surface of the sleeve, and a machining apparatus therefor.
[0002]
[Prior art]
In recent years, with the increase in performance of bearing application devices, devices using fluid bearings are increasing. In this type of hydrodynamic bearing, as shown in FIG. 8, a shaft 10 is rotatably inserted into the inner diameter of a sleeve 4 having a dynamic pressure generating groove 9 on the inner peripheral surface, and a gap between the shaft 10 and the sleeve 4 is lubricated. The agent is injected, and when either one of the shaft 10 or the sleeve 4 rotates, pressure is generated by the pumping action of the dynamic pressure generating groove 9 and rotates with high accuracy without contact.
[0003]
A conventional processing method and apparatus for this type of grooved hydrodynamic bearing will be described with reference to FIGS. Conventionally, as a method of processing the dynamic pressure generating groove 9 on the inner peripheral surface of the sleeve 4 made of a metal material or the like, two processes, a pre-groove process and a groove process, are required.
As a conventional dynamic pressure generating groove processing apparatus, FIG. 9 shows an apparatus for performing a pre-groove process, and FIG. 10 shows an apparatus for performing a groove processing process. In the pre-groove process, the inner peripheral surface 6 of the hole 20 is smoothed by inserting it into the hole 20 of the hard ball 5 sleeve 4 supplied to the center of the sleeve 4 by the pin 1 as shown in FIG. Next, in the grooving step, as shown in FIG. 10, either the guide shaft 2 or the sleeve 4 is incorporated into the guide shaft 2 by giving a feed at a relative speed V to the rotation of the rotational speed W. A dynamic pressure generating groove 9 is formed on the inner peripheral surface 6 of the sleeve 4 by plastic working with the hard rolled balls 3A and 3B. In processing the herringbone-shaped dynamic pressure generating groove 9 as shown in FIG. 8, when the rolling balls 3 </ b> A and 3 </ b> B advance to the approximate center of the hole 20 of the sleeve 4 in FIG. Can be formed by switching the rotation direction to the reverse rotation without changing the feed speed V.
[0004]
FIG. 11 shows a conventional dynamic pressure generating groove machining process. The pre-groove process corresponds to steps # 1 to # 3 in FIG. In step # 1, the sleeve 4 is set, and in step # 2, the ball 5 is inserted into the inner peripheral surface b of the hole 20 of the sleeve 4, and then the sleeve 4 is taken out in step # 3. The groove processing steps correspond to steps # 4 to # 6 in FIG. In step # 4, the sleeve 4 is set. In step # 5, grooves are formed by the rolling balls 3A and 3B. In step # 6, the sleeve 4 is taken out.
[0005]
[Problems to be solved by the invention]
Generally, in the field of machine part machining, it is required for machining apparatuses used for mass production to reduce machining processes in order to shorten machining tact and reduce machining costs.
An object of the present invention is to provide a dynamic pressure generating groove processing method and apparatus capable of reducing a processing step in processing of a hydrodynamic bearing having a dynamic pressure generating groove.
[0006]
[Means for Solving the Problems]
In order to achieve this object, the present invention has a pin portion and a rolled ball portion in a dynamic pressure generating groove processing apparatus.
By this. The step of finishing the inner peripheral surface by inserting the ball into the sleeve of the fluid dynamic bearing and the step of finishing the dynamic pressure generating groove processing can be performed continuously, and the number of processing steps can be reduced.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, a pin that inserts a ball into the inner peripheral surface of a sleeve by a tip portion to finish a prepared hole, and extends from the pin, and is perpendicular to the axis of the pin. And a guide shaft having a plurality of rolling balls radially, and the sleeve is finished by applying rotation and feed in the direction of the rotation axis to at least one of the sleeve and the guide shaft. This is a dynamic pressure generating groove processing device that inserts the guide portion into the inner peripheral surface of the pilot hole and processes the dynamic pressure generating groove with the rolled ball, and continuously performs the insertion of the ball and the dynamic pressure generating groove processing. Therefore, the working process can be shortened.
[0008]
The invention according to claim 2 is a dynamic pressure generating groove processing apparatus according to claim 1, further comprising a load cell for measuring an insertion load of the ball and the guide shaft, wherein the ball is inserted and the dynamic pressure generating groove is processed. In addition, it is possible to obtain the inner diameter of the sleeve hole before processing the dynamic pressure generating groove by calculating and converting the load at the time of ball insertion measured by the load cell. Is possible. Moreover, the maximum outer diameter of the rotating circle formed by the rolling ball when the guide shaft rotates can be obtained by calculating and converting the load at the time of machining the dynamic pressure generating groove measured by the load cell. It has the effect that it is possible to manage the wear of the.
[0009]
The invention according to claim 3 is the dynamic pressure generating groove processing apparatus according to claim 1 or 2, wherein the guide shaft concentric convex portions are provided, and the ball insertion and the dynamic pressure generating groove processing are performed. It is possible to carry out continuously, and it is possible to perform deburring after machining the dynamic pressure generating groove by the convex portion provided in the guide shaft. Further, when the convex portion is inserted into the dynamic pressure generating groove, the dynamic pressure generating groove depth can be obtained by calculating and converting the load measured by the load cell, and the processing accuracy can be managed. Have
[0010]
According to a fourth aspect of the present invention, a pin and a guide shaft extending from the pin and having a plurality of rolling balls in a direction perpendicular to the axis of the pin are used on the inner peripheral surface of the sleeve. The step of finishing the prepared hole by inserting a ball by the tip of the pin, and performing the finishing process by applying rotation and feed in the rotation axis direction to at least one of the sleeve or the guide shaft A dynamic pressure generating groove machining method comprising a step of inserting the guide portion into an inner peripheral surface of a pilot hole of a sleeve and machining a dynamic pressure generating groove with the rolled ball. The generated groove can be continuously processed, and the working process can be shortened.
[0011]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of an essential part of a hydrodynamic groove generating apparatus for a hydrodynamic bearing according to a first embodiment of the present invention.
In FIG. 1, 1 is a pin for inserting a ball 5 into a sleeve 4, and 3 </ b> A and 3 </ b> B incorporated in the guide shaft 2 are rolled to form a dynamic pressure generating groove on the inner peripheral surface 6 of the sleeve 4. It is a ball. The pin 1 is configured on the same axis as the guide shaft 2. The rolling balls 3 </ b> A and 3 </ b> B are hard balls, ceramic balls or the like, and a material that is harder than the sleeve 4 is selected.
[0012]
The operation of the hydrodynamic groove generating apparatus for a hydrodynamic bearing configured as described above will be described with reference to FIG. In FIG. 1, the inner peripheral surface 6 is smoothed by inserting a hard ball 5 supplied to the opening of the pilot hole 20 of the sleeve 4 by the pin 1 into the pilot hole 20 of the sleeve 4, and then the guide shaft 2 or By applying a feed of a relative speed V to the sleeve 4 along with the rotation of the rotational speed W, the pilot hole 20 of the sleeve 4 is plastically processed by the hard rolling balls 3A and 3B incorporated in the guide shaft 2. A dynamic pressure generating groove is formed on the inner peripheral surface 6.
[0013]
FIG. 2 is a cross-sectional view of the main part of the hydrodynamic groove generating apparatus for a hydrodynamic bearing according to the second embodiment of the present invention. The same components as those in the first embodiment shown in FIG. Description is omitted.
Here, the difference from the first embodiment is that the load cell 7 is attached to the guide shaft 2.
[0014]
The operation of the hydrodynamic groove generating apparatus for a hydrodynamic bearing configured as described above differs from that of the first embodiment in that the load when the ball 5 is inserted into the pilot hole 20 of the sleeve 4 by the load cell 7 is as follows. By measuring and converting the numerical value by a computer or the like, the inner diameter D of the pilot hole 20 of the sleeve 4 before the dynamic pressure generating groove processing can be obtained. FIG. 3 shows a graph of the relationship between the load measured by the load cell 7 when the ball 5 is inserted and the inner diameter D of the pilot hole 20 of the sleeve 4. There is a relationship in which the load cell load decreases as the sleeve inner diameter D increases. This makes it possible to manage the accuracy of the sleeve components.
[0015]
Another difference from the first embodiment is that the load at the time of machining the dynamic pressure generating groove is measured by the load cell 7, and the numerical value is arithmetically converted by a computer or the like to rotate the guide shaft 2 when the guide shaft 2 rotates. The maximum outer diameter D ′ of the rotating circle formed by the rolling ball incorporated in 2 can be obtained. FIG. 4 is a graph showing the relationship between the load measured by the load cell 7 during machining of the dynamic pressure generating groove and the maximum outer diameter D ′ formed by the rolled ball. There is a relationship in which the load cell load decreases as the maximum outer diameter D ′ formed by the rolled ball decreases. This makes it possible to manage the wear of the rolled ball.
[0016]
FIG. 5 shows a cross-sectional view of the main part of a hydrodynamic groove generating apparatus for a hydrodynamic bearing according to a third embodiment of the present invention, with the same components as those of the first and second embodiments (FIGS. 1 and 2). Indicate the same reference numerals, and the description thereof is omitted.
Here, the difference from the first and second embodiments is that the guide shaft 2 is provided with convex portions 8 concentrically.
[0017]
In the operation of the hydrodynamic groove generating apparatus for a hydrodynamic bearing configured as described above, the operation different from the operation in the first and second embodiments is performed by the rolling balls 3A and 3B incorporated in the guide shaft 2. This is a point that the processing burr generated when the dynamic pressure generating groove is formed in the inner peripheral surface 6 of the pilot hole 20 of the sleeve 4 is deburred by the convex portion 8.
Another difference from the first and second embodiments is that the load when the convex portion 8 is inserted into the dynamic pressure generating groove formed by the spotting balls 3A and 3B is measured from the load cell 7, The numerical value is arithmetically converted by a computer or the like to obtain the groove depth H of the dynamic pressure generating groove formed on the inner peripheral surface 6 of the pilot hole 20 of the sleeve 4 shown in FIG. FIG. 6 is a graph showing the relationship between the load measured by the load cell 7 when the convex portion 8 is inserted into the dynamic pressure generating groove and the dynamic pressure generating groove depth H. There is a relationship in which the load cell load decreases as the dynamic pressure generating groove depth H increases. This makes it possible to manage the dynamic pressure generating groove depth.
[0018]
FIG. 7 shows the processing steps in the embodiment of the present invention. The sleeve 4 is set in the sleeve setting process indicated by # 1, the ball 5 is inserted into the pilot hole 20 of the sleeve 4 in the ball insertion process indicated by # 2, and subsequently the rolling process is indicated in # 3. Groove machining is performed on the inner peripheral surface 6 of the prepared hole 20 by the balls 3A and 3B, and then deburring is performed by the convex portion 8 in the deburring process indicated by # 4. These series of steps are continuously performed in a series of relative movements of the guide shaft 2 and the sleeve 4. Note that the deburring of the process indicated by # 4 may not be performed.
[0019]
【The invention's effect】
As described above, the dynamic pressure generating groove processing apparatus of the present invention has a pin at the tip and a plurality of rolled balls at the guide shaft portion, and drills holes and dynamic pressure generating grooves by inserting the balls. An advantageous result is obtained that the machining can be performed in a series of operations and the machining process can be shortened.
[0020]
Further, by calculating and converting the load at the time of ball insertion measured by the load cell, the inner diameter of the sleeve before the dynamic pressure generating groove is processed can be obtained, and the sleeve component accuracy can be managed. In addition, the maximum outer diameter of the rotating circle formed by the rolled ball can be obtained by calculating and converting the load at the time of machining the dynamic pressure generating groove measured by the load cell, and the wear of the rolled ball can be managed. The advantageous result is obtained.
[0021]
Furthermore, the convex portion provided on the guide shaft enables deburring after the dynamic pressure generating groove is processed, and the load measured when the convex portion is inserted into the dynamic pressure generating groove is calculated and converted. An advantageous result is obtained that the dynamic pressure generating groove depth can be obtained and the processing accuracy can be managed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a dynamic pressure generating groove processing apparatus according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part of a dynamic pressure generating groove processing apparatus according to a second embodiment of the present invention. 3 is a graph showing the relationship between the load cell load and the inner diameter of the sleeve pilot hole in the second embodiment of the present invention. FIG. 4 shows the maximum outside of the circle formed by the load cell load and the rolled hole in the second embodiment of the present invention. FIG. 5 is a cross-sectional view of a main part of a dynamic pressure generating groove processing apparatus according to a third embodiment of the present invention. FIG. 6 is a load cell load and dynamic pressure generation according to the third embodiment of the present invention. Fig. 7 is a graph showing the relationship with the groove depth. Fig. 7 is a diagram of the machining process of the dynamic pressure generating groove machining method in the embodiment of the present invention. Cross-sectional view of the main part of the processing device in the pre-groove process of the generating groove processing device 【 10] Description of prior art cross sectional view of a processing apparatus in a groove processing step of the dynamic pressure generating groove machining device [of 11] Conventional hydrodynamic groove machining process Fig. [Code]
1 Pin 2 Guide shafts 3A and 3B Rolled balls 4 Sleeves 5 Balls 6 Inner peripheral surfaces 7 Load cells 8 Convex portions 9 Dynamic pressure generating grooves 10 Axes

Claims (4)

  A pin that inserts a ball into the inner peripheral surface of the sleeve by the tip and finishes the pilot hole, and a plurality of rolled balls that extend from the pin and radiate in a direction perpendicular to the axis of the pin A guide shaft, and at least one of the sleeve and the guide shaft is rotated and fed in the direction of the rotation shaft, thereby the guide portion is provided on the inner peripheral surface of the prepared hole of the sleeve. A dynamic pressure generating groove processing apparatus that inserts and processes a dynamic pressure generating groove with the rolled ball.   The dynamic pressure generating groove machining apparatus according to claim 1, further comprising a load cell that measures an insertion load of the ball and the guide shaft.   3. The dynamic pressure generating groove processing apparatus according to claim 1, wherein concentric protrusions are provided on the guide shaft. Using a pin and a guide shaft extending from the pin and having a plurality of rolling balls radially perpendicular to the pin axis, the ball is inserted into the inner peripheral surface of the sleeve by the tip of the pin. A finishing process of the pilot hole, and applying rotation and rotation axis direction feed to at least one of the sleeve or the guide shaft, thereby providing an inner peripheral surface of the pilot hole of the sleeve that has been finished. A dynamic pressure generating groove machining method for continuously performing the process of inserting the guide portion and machining the dynamic pressure generating groove with the rolled ball.

Images