JPS5912884B2 - Rotating shaft for spherical hydrodynamic bearing and manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating shaft for a spherical hydrodynamic bearing and a method for manufacturing the rotating shaft.

In this type of spherical hydrodynamic bearing, there are those in which the shaft and sphere are made separately and joined together by appropriate joining means, and those in which the shaft and sphere are processed into one piece.

In this spherical hydrodynamic bearing, its load capacity is largely influenced by the rotational speed of the rotating shaft and the grooves carved on the spherical surface.

As the rotational speed increases, even the slightest eccentricity of the rotating shaft has a greater effect, so special attention is paid to this eccentricity.
Furthermore, when the number of rotations is particularly high, the strength of the rotating shaft becomes a problem. In order to reduce the eccentricity mentioned above, when machining the rotating shaft, there are different difficulties in machining, depending on whether the shaft and sphere are separate or integrated. However, it is difficult to keep the roundness of the sphere within the desired value, and if they are machined separately, there is a concern that they will be misaligned when they are combined. Furthermore, when separately processed parts are joined together, the strength of their joints becomes a problem; if the strength of their joints is weak, there is a risk that the two parts will separate during high-speed rotation or long-term rotation.

As an example of machining these separate bodies, a long hole is made in the sphere, a protrusion that fits into the long hole is provided at the tip of the shaft, the protrusion is inserted into the long hole, and the body is integrated by an appropriate coupling means 35. There is a rotating shaft connected to b゛, when machining the shaft, the diameter of the protrusion 1
Because of the wire, only small center holes can be machined, and the finish of the center hole is not very good. Furthermore, it is difficult to process this center hole, and the efficiency of grinding using this small center hole becomes extremely low. The purpose of this invention is to provide a rotating shaft of a spherical hydrodynamic bearing and a method for manufacturing the same, which minimizes the above-mentioned drawbacks.The shaft and the sphere are made separately and welded together. A concave spherical surface corresponding to the sphere is formed at the tip of the spherical body, and a long hole is drilled in the shaft center.A long hole with the same diameter as the long hole of the shaft is also drilled in the sphere toward the center of the sphere. A rotating shaft for a spherical hydrodynamic bearing, in which a pin is fitted to connect the two to a shank, and a joint surface between the concave spherical surface and the spherical body is welded, and a method for manufacturing the same.

Next, embodiments of the present invention will be described with reference to the drawings. 1 is a metal shaft, and a sphere 2 is welded to the tip of the shaft.

3 is a pin provided to align the spherical center 21 of the sphere 2 with the axis 11 of the shaft 1, and the thickness of this pin is usually the diameter of the elongated hole 12 in the axial direction drilled at the tip of the shaft 1. It is formed to be extremely slightly narrower than the diameter of the elongated hole 22 bored in the sphere 2, and its length is slightly shorter than the total length of the elongated hole 12 of the shaft 1 and the elongated hole 22 of the sphere 2. There is.

The joint surface 4 between the sphere 2 and the shaft 1 has a concave spherical surface substantially equal to the spherical surface of the sphere 2 formed on the shaft 1, and the joint surface is firmly fixed by welding. Next, a method for manufacturing the above rotating shaft for a spherical hydrodynamic bearing will be explained.

The sphere 2 is formed into a nearly perfect sphere by grinding, lapping, etc., according to a normal steel ball manufacturing method. A long hole 22 with an accurate shape and dimensions is formed by drilling or electrical discharge machining or other machining means toward the spherical center 21 of the sphere 2.
are formed so that the center lines of the spherical center 21 and the elongated hole 22 coincide. In the missing process, the elongated hole 22 of this sphere 2 is used, and the third
By electric discharge machining using the jig 5 shown in the figure,
A necessary groove 23 as a spherical bearing is machined on the surface of the sphere 25. A concave spherical surface 51 having a radius approximately equal to that of the sphere 2 is formed at the tip of this jig 5, and a concave spherical surface 51 is formed at the tip of the jig 5. A long hole 52 having the same diameter as the long hole 22 of the sphere 2 is machined along the center line.

Further, this jig is machined so that the axes of the reference surfaces 53, 54 and the threaded portion 55 exactly coincide with the spherical center of the concave spherical surface 51 in order to align with other jigs and tools. Prior to electrical discharge machining, the jig 5 is fixed to the fixture 6 by the threaded portion 55 with the reference surfaces 53 and 54 aligned with the machining reference surfaces 61 and 62 of the fixture 6 of the electrical discharge machine. Next, a pin 3 having a diameter slightly smaller than the diameter of the elongated hole is inserted into the elongated hole 52 machined in this jig 5.
is inserted, and the elongated hole 22 of the sphere 2 is fitted into this pin 3.
At this time, the surface of the sphere 2 comes into close contact with the concave spherical surface of the jig 5, and the sphere 2 is perfectly positioned on the jig 5. In this way, sphere 2
After the setting of the sphere 2 is completed, the electrode 63 of the electric discharge machine
A required groove is formed on the surface of the ball 2 with the axis of the elongated hole and the ball center 21 of the sphere 2 almost completely aligned. Although the above-mentioned groove machining was performed by electrical discharge machining, this groove machining can also be performed by photo etching.

Next, an example of the addition of axis 1 will be described. The shaft 1 can have various shapes depending on where it is used, but a center hole 13 necessary for lathe processing or grinding is machined at one end, and a sphere 2 is machined at the other end.
A concave spherical surface 14 corresponding to the spherical surface of the sphere is formed by turning, wrapping, etc., and an elongated hole 12 with the same diameter as the elongated hole of the sphere 2 is formed.
is formed by turning, reaming, etc. In this case, the concave spherical surface and the elongated hole are machined using the same chuck on a lathe.

Therefore, the concave spherical surface and the center of the elongated hole are aligned and serve as a reference surface for turning, grinding, etc. of other parts of the shaft, which also has an effect on accuracy, processing efficiency, etc. Next, a conical depression center 71 as shown in FIG. 5 is placed in the center hole 13 of the shaft 1.
A ball center 72 having a rotatably held steel ball is applied to the concave spherical surface 14, and the shaft is finished by a cylindrical grinder equipped with a grinding wheel 73.

This processing is performed without slippage b between the concave spherical surface 14 of the shaft 1 and the steel ball of the ball center 72, and the misalignment between the spherical center of the concave spherical surface 14 and the axis of the shaft 1 is removed, and both is an exact match. Furthermore, instead of the ball center 72 described above, a hydrostatic fluid bearing can also be used. Next, the sphere 2 processed as described above is joined to this shaft 1.

To do this, insert the pin 3 into the elongated hole 12 of the shaft 1 and the elongated hole 22 of the sphere 2, lightly fix them together, and hold them in a state where force is applied in the axial direction as shown in Figure 6. 2 and the joint surface with the shaft 1, that is, the concave spherical surface, are welded by electron beam welding, laser welding, resistance welding, or the like. In the figure, 81 is an inverted center with a conical concave surface at one end, 82 is a coil spring, and a sleeve 83 is fitted around the outer periphery of the inverted center, and this sleeve 83 is slidably attached to an axle box 84. It is supported by a pair of ball bearings 85. This ball bearing 8
5, a hydrostatic fluid bearing can also be used. 86
is a conical deposit center, and welding is performed between the deposit center 86 and the reverse center 81 while rotating the rotary shaft 1 and the sphere 2 while being held in close contact with each other by the spring force of the coil spring.

In the previous embodiment, a cylindrical pin was used, but if a slit 32 extending in the axial direction as shown in FIG. When welding is performed, the bottom of the elongated hole of the shaft or sphere and the pin 31
Since the air trapped in the gap formed by the end face of the weld can be easily removed, there is no residual air flowing in from the gap during welding, so welding can be carried out reliably.

Furthermore, if a metal with a high Young's modulus is selected as the material for the pin, a stronger rotating shaft can be obtained than in the case of pins made of commonly used metals.

Since the rotating shaft for a spherical hydrodynamic bearing of the present invention is constructed as described above, the spherical center of the sphere reliably coincides with the axial center of the shaft.
It is a highly accurate rotating shaft with little eccentricity.

Therefore, it is suitable for high-speed rotation, and since eccentricity is small, the risk of separation of the shaft and sphere is extremely reduced. Furthermore, if the pin is made of a material with a high Young's modulus, in addition to the welding strength described above, the strength of the pin material will be added, so a protrusion is provided at the tip of the shaft to fit it into the elongated hole of the sphere. A rotary shaft with higher rigidity than a conventional rotary shaft bonded together can be obtained. In addition, regarding the manufacturing process, the shaft and sphere are manufactured separately, and the grooves on the sphere surface, which are currently relatively prone to machining errors, can be machined in an intermediate process, so the loss due to machining errors is only for the sphere. , the losses can be much lower than in the case of machining a one-piece shaft.

Furthermore, in the process of machining the shaft, the concave spherical surface and the elongated hole are machined using the same chuck, so the spherical center of the concave spherical surface and the center of the elongated hole coincide. Therefore, turning and grinding other parts of the shaft can be performed using this concave spherical surface as a reference surface, which is effective in terms of accuracy and efficiency, and as a result, a highly precisely machined sphere and a rotating shaft with little eccentricity can be obtained. That's why.

[Brief explanation of drawings]

Fig. 1 is a partially longitudinal front view of a rotating shaft showing an embodiment of the invention, Figs. 2 to 6 relate to the manufacturing method of the invention, and Fig. 2 is an enlarged sectional view of a sphere. , Fig. 3 is an enlarged explanatory diagram showing the relative position between the jig and the sphere when performing electric discharge machining to form a predetermined groove on the surface of the sphere, Fig. 4 is a partially vertical front view of the shaft, and Fig. 5 is a An explanatory diagram of the finishing process of the shaft. Figure 6 is a partial longitudinal cross-sectional schematic diagram of a device that rotates the shaft and sphere while keeping them in close contact during the welding process. Figure 7 is used when joining the shaft and sphere. FIG. 3 is an enlarged perspective view of a special pin. Explanation of the symbols: 1 is the shaft, 2 is the sphere, 3 is the pin, 4 is the joint surface, 5 is the jig, 6 is the fixture, 11 is the shaft center, 12 is the elongated hole, 1
4 is a concave spherical surface, 21 is a spherical center, 22 is an elongated hole, 23 is a groove, 31
is a special pin, 51 is a concave spherical surface, 52 is a long hole, 71 is a conical deep center, 72 is a ball center, 81 is a reverse center,
82 is a coil spring, and 86 is a conical depression center.

Claims (1)

[Scope of Claims] 1. A shaft having an elongated hole drilled in the axial direction concentrically with the axis at the tip, and an elongated hole with the same diameter as the elongated hole drilled toward the center of the sphere, and is a sphere having a predetermined groove, a pin having a length slightly shorter than the sum of the depths of the elongated hole in the shaft and the sphere, and fitted into the elongated hole in order to combine the shaft and the sphere, and the aforementioned pin. A rotating shaft for a spherical hydrodynamic bearing, characterized in that the joint between the shaft and the sphere is fixed by welding. 2. The spherical dynamic pressure bearing rotating shaft according to claim 1, wherein the pin fitted into the elongated hole of the shaft and the sphere is a pin having a slit extending in the axial direction. 3. The rotating shaft for a spherical dynamic pressure bearing according to claim 1, wherein the pin fitted into the long hole of the shaft and the sphere is a metal pin having a high Young's modulus. 4. Drill a long hole in the sphere toward the center of the ball, insert a pin whose outer diameter is slightly smaller than the diameter of the long hole, and photo-etch the surface of the sphere using this pin and a part of the surface of the sphere as a reference surface. A rotating machine for spherical hydrodynamic bearings in which a predetermined groove for a spherical hydrodynamic bearing is machined using processing means such as electrical discharge machining or electroforming, and the grooved sphere is welded to the tip of a shaft machined in a separate process. How to manufacture the shaft. 5. In the method for manufacturing a rotating shaft for a spherical hydrodynamic bearing described in claim 4, a concave spherical surface corresponding to the spherical surface of the sphere to be joined is formed at one end of the shaft, and a pin is provided concentrically with the shaft center. A state in which the sphere and shaft are combined by cutting a slotted hole slightly larger than the outside diameter of the ball and inserting a pin slightly shorter than the sum of the depths of the slotted hole of the sphere and the slotted hole of the shaft into both slotted holes. A method for manufacturing a rotating shaft for a spherical hydrodynamic bearing in which the joints are welded.