JPH045291Y2 - - Google Patents

Description

[Detailed explanation of the invention] a. Purpose of the invention (industrial application field) The mold for forming the bearing body of the bearing according to this invention is:
Video equipment including video decks, office equipment,
It is used when the bearing body of a bearing that precisely supports the rotating parts of audio equipment, etc. with minimal resistance is integrally molded from synthetic resin, and the bearing surface of the bearing body can be formed into the desired size and shape. , to ensure accurate finishing.

(Prior art) As an example of a bearing that rotatably supports a shaft incorporated in the various devices mentioned above, for example, a bearing that uses the dynamic pressure of a fluid such as air or oil generated as the shaft rotates is used. A hydrodynamic bearing is used to support this shaft with minimal resistance and precise dimensions.

Figures 5 and 6 show a hydrodynamic bearing disclosed in Japanese Utility Model Publication No. 61-31538 as an example of such a bearing. Based on this, the structure and operation of the hydrodynamic bearing will be briefly explained.

At two positions above and below the cylindrical wall 8 formed on the bearing body 2 which has the mounting flange 1 formed at the lower end,
Bearing surfaces 3, 3 whose inner diameter is smaller than other parts
is formed, and the lower end opening of the cylindrical wall 8 is closed by the thrust receiving plate 4.

On the outer peripheral surface of the rotating shaft 5 inserted into the cylinder wall 8 from above, in the portion facing the bearing surfaces 3, 3, there are chevron-shaped dynamic pressure generating grooves 6, 6 that generate support pressure in the radial direction. A plurality of dynamic pressure generating grooves 7, 7 are formed on the lower surface of the rotating shaft 5, which faces the upper surface of the thrust receiving plate 4, for generating support pressure in the thrust direction. .

The dynamic pressure generating grooves 6, 6 for radial bearings are formed on the bearing surfaces 3, 3 instead of being formed on the outer peripheral surface of the rotating shaft 5.
Similarly, dynamic pressure generating grooves 7, 7 for thrust bearings may also be formed on the upper surface of the thrust receiving plate 4.

In the hydrodynamic bearing formed as described above, when the rotating shaft 5 rotates in the direction of the arrow a in FIGS.
3 and the outer circumferential surface of the rotating shaft 5 (in actual cases, the width of this gap 9 is several microns to several tens of microns).
The fluid existing inside the rotating shaft 5 and the fluid existing between the lower surface of the rotating shaft 5 and the upper surface of the thrust receiving plate 4 flow along the respective dynamic pressure generation grooves 6 and 7, thereby generating pressure that presses the outer surface of the rotating shaft 5. occurs, and the rotating shaft 5 is supported by the bearing surfaces 3, 3 of the cylinder wall 8 and the thrust receiving plate 4 via a layer of pressure fluid. Effects when the dynamic pressure generating grooves 6, 7 are formed on the bearing surfaces 3, 3 and the upper surface of the thrust receiving plate 4, or when the shaft is fixed and the cylinder wall 8 and the thrust receiving plate 4 are rotated. This is also the case.

By the way, the bearing body 2 incorporated in a bearing such as a hydrodynamic bearing configured and operated as described above is
It is considered that by integrally molding the thrust bearing plate 4 of synthetic resin together with the thrust receiving plate 4 that closes the opening at the lower end of the cylinder wall 8, it is possible to facilitate the manufacture of the bearing and stabilize its quality.

That is, for example, as shown in FIGS. 7 and 8, the cylindrical portion 13
A bearing body 15 made of integrally molded synthetic resin such as thermoplastic resin or thermosetting resin is fitted inside a metal holder 14 having a mounting flange 1 formed at the lower end thereof. This bearing body 15
By inserting the holder 14 into a mold for molding when molding the bearing body 15, the molding of the bearing body 15 and the fitting into the holder 14 can be performed simultaneously.

In this way, the bearing body 1 is made by integral molding of synthetic resin and is fitted into the holder 14 at the same time as the molding.
5 is formed into a bottomed cylindrical shape consisting of a cylindrical wall 16 and a bottom wall 17 that closes the lower end of the cylindrical wall 16.

In the example shown in FIGS. 7 and 8, the cylinder wall 16
The inner circumferential surface of the radial bearing surfaces 18 and 18 are made by making the inner diameter slightly smaller than the other portions at two positions, the upper and lower positions, and each radial bearing surface 1
8 and 18, a plurality of chevron-shaped grooves 19 and 19 for generating dynamic pressure are formed, respectively.

In this way, the radial bearing surfaces 18, 18 are formed at two positions above and below the inner peripheral surface of the cylinder wall 16, and
A shaft 20 that rotates relative to the bearing body 15 is inserted into the bearing body 15 in which grooves 19, 19 for generating dynamic pressure are formed in the radial bearing surfaces 18, 18.

A hemispherical protrusion 22 is formed at the center of the upper surface of the bottom wall 17 that closes the lower end opening of the cylindrical wall 16, and supports the center of the lower surface of the shaft 20. This protrusion 2
2, for generating dynamic pressure for the thrust bearing.
A plurality of spiral dynamic pressure generating grooves 23, 23 are formed.

Further, small holes 21 are formed in the corners of the bottom wall 17, and the fluid sealed between the upper surface of the bottom wall 17 and the lower surface of the shaft 20 is discharged to the outside through the small holes. The shaft 20 can be easily inserted.

In the hydrodynamic bearing configured as described above, when the shaft 20 rotates with respect to the bearing body 15 in the direction of arrow b in FIGS. Dynamic pressure is generated between the radial bearing surfaces 18, 18 and the outer peripheral surface of the shaft 20 by the grooves 19, 19 formed in the grooves 19, 19, so that the shaft 20 is supported in the radial direction.

Further, as the shaft 20 rotates, dynamic pressure is generated between the lower surface of the shaft 20 and the upper surface of the bottom wall 17 by the dynamic pressure generating grooves 23, 23 on the upper surface of the bottom wall 17, and this dynamic pressure Therefore, the shaft 20 is supported in the thrust direction.

Further, as another example of a hydrodynamic bearing using an integrated bearing body 15, a structure as shown in FIGS. 9 and 10 has been considered.

In the case of the structure shown in FIGS. 9 and 10, the projection 22 is not formed on the top surface of the bottom wall 17 of the bearing body 15 as in the example shown in FIGS. By curving the lower surface of 20 into a spherical shape, this shaft 2
The contact area between the lower surface of 0 and the upper surface of the bottom wall 17 is made small.

By the way, when the bearing body 15 including the cylindrical wall 16 and the bottom wall 17 as described above is integrally molded from synthetic resin, a mold as shown in FIG. 11 is used.

This mold has a bearing body 15 due to its inner circumferential surface.
A first type element 25 having a hole 24 forming the outer peripheral surface of the cylindrical wall 16 forming the bearing body 15, and a bottom forming the bearing body 15 by closing one end opening of the hole 24 formed in the first type element 25. A second type element 26 forms the outer surface of the wall 17, and has an outer diameter smaller than the inner diameter of the hole 24, is inserted into the hole 24 concentrically with the hole 24 during molding, and has a tip end surface 27a. and the second type element 26, there is a third type element 27 forming a space 28 for forming the bottom wall 17, and an outer peripheral surface of the third type element 27 and an inner peripheral surface of the hole 24. The supply port 30 uniformly feeds the synthetic resin into the cylindrical space 29 from the end opening of the cylindrical space 29 for forming the cylindrical wall 16, which is formed in between.

The cylinder wall 16 is formed by the mold configured as described above.
In order to form a bearing body 15 including a bottom wall 17 and a bottom wall 17,
When molding synthetic resin, a heated and molten thermoplastic resin or an uncured thermosetting resin is injected into the cylindrical space 29 from a supply port 30 provided at an end opening of the cylindrical space 29 .

The uncured synthetic resin injected into the cylindrical space 29 from the supply port 30 flows as shown by the arrow in FIG. hardens within the cylindrical space 29,
A bearing body 1 in which a cylinder wall 16 and a bottom wall 17 are integrated
It becomes 5.

(Problem to be solved by the invention) However, the bearing body 15 including the cylinder wall 16 and the bottom wall 17 as described above is integrally made of synthetic resin using a mold as shown in FIG. When molding,
This causes the following inconvenience.

That is, the uncured synthetic resin injected into the cylindrical space 29 from the supply port 30 flows as shown by the arrow in FIG. The synthetic resin is cured in the cylindrical space 29, but the presence of air bubbles in the uncured synthetic resin due to air mixed in, air present in the mold, and gas generated from the synthetic resin is avoided. do not have.

Such bubbles tend to gather in the center of the space 28 where the ends of the synthetic resin that have reached the space 28 from the cylindrical space 29 collide with each other, but the third type element 27
When air bubbles are concentrated on the tip surface 27a, the dynamic pressure generating groove 23 formed by this tip surface 27a,
The shape of the protrusion 22 (examples shown in FIGS. 7 and 8) becomes irregular, and the hydrodynamic bearing assembled using this bearing body 15 no longer exhibits the expected performance.

When the dynamic pressure generating groove 23 is provided on the shaft 20 side, the inner surface of the bottom wall 17 formed by the tip surface 27a of the third type element 27 becomes a mere flat surface.
Similarly, even if the shape of this flat surface becomes unstable due to the inclusion of air bubbles as described above, the hydrodynamic bearing will no longer exhibit the expected performance.

The mold for molding the bearing body of the bearing of this invention is designed to prevent the formation of air bubbles caused by air mixed in the synthetic resin, air existing in the space inside the mold, and gas generated from the synthetic resin. third type element 27
By configuring it so that it does not concentrate on the tip surface 27a of the
This solves the above-mentioned inconveniences.

b. Structure of the invention (means for solving the problem) The mold for forming the bearing body of the bearing of the invention is circular,
Alternatively, the cylinder wall is shaped like a cylinder with a bottom and includes a cylinder wall having a non-circular arbitrary outer peripheral shape and a bottom wall that closes the lower end of the cylinder wall, and a radial bearing surface is formed on the inner peripheral surface of the cylinder wall, and In order to integrally mold the above-mentioned bearing body with a synthetic resin, which is incorporated into a bearing in which a shaft is inserted into the bearing body with the inner surface of the bottom wall as a thrust bearing surface, and the shaft and the bearing body can freely rotate relative to each other. use.

The mold of the present invention used for such a purpose has a first mold having a hole whose inner peripheral surface forms the outer peripheral surface of the cylindrical wall, as in the case of the conventional mold described above. a second type element that closes an opening at one end of the hole formed in the first type element and forms an outer surface of the bottom wall; A third type element is inserted into the hole concentrically with the hole and forms a space for forming the bottom wall between the distal end surface of the third type element and the second type element; and a supply port that uniformly feeds the synthetic resin into the cylindrical space from an end opening of the cylindrical space for forming the cylindrical wall, which is formed between the outer peripheral surface and the inner peripheral surface of the hole. ing.

In the mold for forming the bearing body of the bearing according to the present invention, which comprises the first to third type elements and the supply port as described above, the surface of the second type element faces the space for forming the bottom wall. A weir plate portion is formed in the portion extending in the diametrical direction of the third type element.

The height dimension of this weir plate part is smaller than the thickness of the space for forming the bottom wall, and this weir plate part divides the space into a first space and a second space, and also divides the space into a first space and a second space. Both the second spaces are communicated through a slit-shaped passageway that is in contact with the distal end surface of the third type element.

Furthermore, means is provided to make the volume of the first space and the volume of the second space, which are configured by partitioning the space for forming the bottom wall with a weir plate part, different from each other.

(Function) When a bearing body having a cylindrical wall and a bottom wall is manufactured by integral molding of synthetic resin using the mold for molding the bearing body of the present invention constructed as described above, it is possible to manufacture the bearing body having a cylinder wall and a bottom wall by integral molding of synthetic resin. As in the case of molding using a mold, this tube is inserted through the supply port provided at the end opening of the cylindrical space formed between the inner peripheral surface of the hole of the first type element and the outer peripheral surface of the third type element. A heated and molten thermoplastic resin or an uncured thermosetting resin is injected into the shaped space.

The uncured synthetic resin injected into the cylindrical space from the supply port flows within this cylindrical space in its length direction, reaches the space for forming the bottom wall, and flows inside this space and the above-mentioned cylindrical space. The bearing body hardens within the bearing body, with the cylindrical wall and bottom wall integrated.

However, in the case of the mold of the present invention, the space for forming the bottom wall is divided into two by the diametrically extending weir plate part of the third type element, and the two divided first and second Since the volumes of the two spaces are different, bubbles due to air or gas mixed in the synthetic resin will not concentrate on the tip end portion of the third type element forming the inner surface of the bottom wall as described above.

In this way, due to the presence of the weir plate that divides the space for forming the bottom wall into two spaces, the first and second spaces having unequal volumes, air and gas bubbles concentrate on the tip surface of the third type element. This is due to the following reasons.

That is, the synthetic resin uniformly fed into the cylindrical space for forming the cylindrical wall flows in the length direction of the cylindrical space and reaches both the first and second spaces at the same time. Since the volumes of the spaces are different, the pressure in the space with the smaller volume increases before the pressure in the space with the larger volume.

Therefore, the synthetic resin subsequently fed into the space with a small volume passes through the slit-shaped passage formed between the edge of the weir plate and the tip surface of the third type element. Air bubbles flow toward a larger space and do not accumulate on the tip end surface of the third type element facing the slit-like passage, thereby preventing the shape of the inner surface of the bottom wall formed by this tip end surface from becoming irregular.

(Example) Next, the present invention will be explained in more detail while explaining the illustrated embodiment.

Figures 1 and 2 show a first embodiment in which the mold for molding the bearing body of the present invention is configured for molding the bearing body of a hydrodynamic bearing, and Figure 1 is a half longitudinal cross-sectional view; FIG. 2 is a sectional view taken along the line AA in FIG. 1.

The mold for forming the bearing body has first to third mold elements 2.
It consists of numbers 5 to 27.

A circular hole 24 is formed in the first type element 25, which passes through the first type element 25 vertically (the upper, lower, left, and right directions are according to the drawing). It forms the outer peripheral surface of the cylindrical wall 16 (see FIGS. 7 and 9).

Further, below the first type element 25, the outer surface of the bottom wall 17 (see FIGS. 7 and 9) is formed by closing the lower end opening of the circular hole 24 formed in the first type element 25. A second type element 26 is provided.

A third type element 27 having an outer diameter smaller than the inner diameter of the circular hole 24 can be inserted into the circular hole 24 of the first type element 25 concentrically with the circular hole 24 during molding. Such a third type element 27
is inserted into the circular hole 24 during molding L
is smaller than the thickness D of the first type element 25 in which this circular hole 24 is formed (L<D), and the third type element 2
7 is inserted into the circular hole 24, its tip surface 2
A space 28 having a thickness d (=D-L) for forming the bottom wall 17 is formed between 7a and the upper surface of the second type element 26.

Further, the outer peripheral surface of the third type element 27 and the circular hole 2
The upper end of the cylindrical space 29 for forming the cylindrical wall 16 is formed between the inner peripheral surface of the cylindrical space 2
A supply port 30 is provided for uniformly feeding the synthetic resin into the cylindrical space 29 from the opening at the upper end of the cylindrical space 29 .

Further, on the upper surface of the second type element 26, the bottom wall 17
A weir plate portion 3 is provided in a portion facing the forming space 28.
1 is formed. The direction in which this weir plate portion 31 is formed is the diametrical direction of the third type element 27 that partitions the upper surface of the space 28, which divides the space 28 into two into a first space 32 and a second space 33.

The height h of this weir plate portion 31 is the same as that of the bottom wall 17.
smaller than the thickness d of the forming space 28 (h<
d) Then, both the first and second spaces 32 and 33 partitioned by this weir plate part 31 are connected to the third type element 2.
7 and the upper edge 31a of the weir plate part 31 through a slit-shaped passage 34. The width W of the weir plate portion 31 is smaller than the inner diameter R of the circular hole 24 of the first type element 25 and larger than the outer diameter r of the third type element 27 (R>W>r),
The distal end surface 27a of the third type element 27 is completely divided into two by the slit-shaped passage 34.

On the other hand, of the first space 32 and the second space 33, which are configured by partitioning the space 28 for forming the bottom wall 17 with the weir plate part 31 as described above, the volume of the first space 32 is the same as that of the first space 32. It is made larger than the volume of the second space 33. That is, a recess 35 is formed on the upper surface of the second type element 26 in a portion that matches the first space 32, and the volume of the first space 32 is made smaller than the volume of the second space 33 by the volume of the recess 35. It's also getting bigger.

By using the mold for molding the bearing body of the bearing of the present invention constructed as described above, the bearing body 15 having the cylindrical wall 16 and the bottom wall 17 as shown in FIGS. When manufacturing by molding, first, the upper end of this cylindrical space 29 is placed in the cylindrical space 29 formed between the inner peripheral surface of the circular hole 24 of the first type element 25 and the outer peripheral surface of the third type element 27. A heated and melted thermoplastic resin or an uncured thermosetting resin is injected through a supply port 30 provided in the opening.

The uncured synthetic resin injected into the cylindrical space 29 from the supply port 30 flows down uniformly within the cylindrical space 29 and reaches the bottom wall 1 which is continuous with the lower end of the cylindrical space 29.
7 formation space 28 is reached.

In this way, the uncured synthetic resin that is uniformly fed into the cylindrical space 29 for forming the cylindrical wall 16 and uniformly flows down inside the cylindrical space 29 is simultaneously transferred to both the first and second spaces 32, 33. Then, both the first and second spaces begin to be filled with uncured synthetic resin.

However, in this case, since the volume of the first space 32 facing the recess 35 is larger than the volume of the second space 33 which is not provided with such a recess, the pressure in the second space 33, which has a small volume, is increased. , the pressure rises earlier than the pressure in the first space 32, which has a large volume.

For this reason, the second space 33, which has a smaller volume after that,
The uncured synthetic resin fed into the weir plate part 3
1 and the top end surface 2 of the third type element 27.
7a, and flows toward the first space 32 having a large volume through the slit-like passage 34 formed between the air and the air.

For this reason, air bubbles do not stay on the tip surface 27a of the third type element 27 facing the slit-shaped passage 34, and the shape of the inner surface of the bottom wall 17 formed by this tip surface 27a becomes indefinite. Things will go away.

Cylindrical wall 16 and bottom wall 1 formed as described above
A recess 35 is provided on the lower surface of the bearing body 15 integrated with the bearing body 15.
A convex portion commensurate with this is formed, but if such a convex portion is a nuisance, it is cut off after the bearing body 15 is removed from the mold.

Next, FIGS. 3 and 4 show a second embodiment of the present invention.

In the case of this embodiment, both the first and second spaces 32, 33
Instead of forming the recess 35 as in the first embodiment on the upper surface of the second type element 26 facing the
6, and the volume of the second space 33 on the side where the convex part 36 is provided is the volume of the first space 32 on the side where the convex part 36 is not provided.
It is smaller than the volume of.

In the case of this embodiment as well, for the same reason as in the case of the first embodiment, the tip surface 27 of the third type element 27
The inner surface shape of the bottom wall 17 formed by a can be accurately finished.

Furthermore, in the case of this embodiment, only a portion of the lower end of the completed bearing body 15 does not protrude (in the case of the first embodiment, the convex portion formed by the recess 35 protrudes). , after molding, this bearing body 1
There is no need to remove a part of 5.

In addition, when the bearing body 15 is fitted inside the holder 14 as shown in FIGS. The circular hole 24 of the type 1 element 25 is formed large enough to fit the holder 14 therein. Of course, a mold in which such a circular hole 24 is formed with a large size is also a target of the present invention.

In addition, in the above-mentioned embodiments, explanations have been given regarding the molding of a hydrodynamic type bearing body with grooves, but the mold of the present invention is suitable for forming a bearing body for such a hydrodynamic type fluid bearing. The invention is not limited and can be used to make bearing bodies for all types of sliding bearings.

c. Effects of the invention Since the mold for molding the bearing body of the bearing of the present invention is configured and operates as described above, even when the bearing body constituting a small bearing is integrally molded from synthetic resin. , it is possible to accurately finish the shape of each part of the bearing body, and the mold ensures that the center of the thrust bearing surface matches the center of the radial bearing surface, and that the thrust bearing surface is perpendicular to the radial bearing surface. This has great industrial effects, such as being able to obtain bearings with stable quality.

[Brief explanation of the drawing]

Figures 1 and 2 show a first embodiment of a mold for forming a bearing body of a bearing according to the present invention, in which Figure 1 is a half longitudinal sectional view, and Figure 2 is a sectional view taken along line A-A in Figure 1. , 3rd-4th
The figure shows a second embodiment of the mold for molding the bearing body of the bearing of the present invention, and FIG. 3 is a half longitudinal sectional view, and FIG.
The figure shows a sectional view taken along line B-B in Fig. 3, Figs. 5 and 6 show a first example of a conventional hydrodynamic fluid bearing, Fig. 5 is a longitudinal sectional view, and Fig. 6 is a bottom view of the shaft. Figures 7 and 8 show a first example of a hydrodynamic bearing incorporating a bearing body manufactured by the mold of the present invention, with Figure 7 being a longitudinal sectional view and Figure 8 being a plan view of the bottom wall portion. , No. 9-1
Figure 0 is a diagram similar to Figures 7 and 8, which also shows the second example.
FIG. 11 is a longitudinal sectional view showing a conventional mold. 1... Flange, 2... Bearing body, 3... Bearing surface, 4... Thrust receiving plate, 5... Rotating shaft, 6, 7
...Dynamic pressure generating groove, 8...Cylinder wall, 9...Gap, 13
... Cylinder part, 14 ... Holder, 15 ... Bearing body,
16...Cylindrical wall, 17...Bottom wall, 18...Radial bearing surface, 19...Groove, 20...Shaft, 21...Small hole, 22...Protrusion, 23...Dynamic pressure generating groove, 24...
...(circle) hole, 25...first type element, 26...second type element, 27...third type element, 27a...tip surface, 28...space, 29...cylindrical space, 30... …
Supply port, 31... Weir plate part, 31a... Upper edge, 3
2...First space, 33...Second space, 34...Passage, 35...Concave portion, 36...Convex portion.

Claims (1)

[Scope of utility model registration request] A bearing having a bottomed cylindrical shape consisting of a cylindrical wall and a bottom wall that closes the lower end of the cylindrical wall, with a radial bearing surface formed on the inner circumferential surface of the cylindrical wall, and a thrust bearing surface formed on the inner surface of the bottom wall. A mold for integrally molding the bearing body from synthetic resin, which is incorporated into a bearing in which a shaft is inserted into the body so that the shaft and the bearing body can freely rotate relative to each other. a first type element having a hole forming an outer circumferential surface of the cylindrical wall; a second type element closing an opening at one end of the hole formed in the first type element and forming an outer surface of the bottom wall;
It has an outer diameter smaller than the inner diameter of the hole, and is inserted into the hole concentrically with the hole during molding, and a space for forming the bottom wall is formed between the tip end surface and the second type element. From the end opening of the cylindrical space for forming the cylindrical wall, which is formed between the outer circumferential surface of the third type element and the inner circumferential surface of the hole,
A supply port for uniformly feeding the synthetic resin into the cylindrical space, and a supply port formed in the surface of the second type element facing the space for forming the bottom wall, extending in the diametrical direction of the third type element. A weir plate portion having a height dimension smaller than the thickness of this space, and a bottom wall forming space divided into two by the weir plate portion into a first space and a second space. A mold for forming a bearing body of a bearing, comprising means for making a volume different from a volume of a second space.