JPS6351850B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a bearing with a creep prevention function, which is employed when a housing made of aluminum or the like is used, and a mold used for carrying out the method.

When using a light alloy containing aluminum as a housing for a rolling bearing, there is a large difference in thermal expansion coefficient between the outer ring of the bearing made of bearing steel and the housing. A gap is formed between the bearings, causing the bearing to rattle within the housing, producing vibration noise, and causing abnormal wear, often leading to the housing being destroyed. To deal with this, for example, as shown in FIG. 1, on the outer periphery of the outer ring 11 of the rolling bearing 1,
Two (sometimes one) circumferential grooves 12 and 13 with a required depth are formed over the entire circumference, and this circumferential groove 1
Rings 14 and 15 made of a synthetic resin material with a high coefficient of thermal expansion, such as 6-6 nylon, inside 2 and 13.
is fitted so that the outer peripheral part protrudes by a minute dimension (usually about 10 to 50 μm) from the outer peripheral surface of the outer ring 11,
If a gap is formed between the inner circumferential surface of the housing and the outer circumferential surface of the outer ring due to the influence of heat, this gap is filled by the thermal expansion of the ring itself, and the housing and bearing 1 are free from the influence of heat. A rolling bearing has been proposed that has a creep prevention function that allows a tightly fitted state to be maintained at all times regardless of the situation.

By the way, when manufacturing the above-mentioned rolling bearing, the following method has conventionally been used. In other words, as mentioned above, there are two
Outer ring 11 formed with parallel circumferential grooves 12 and 13
(It may be assembled as bearing 1), and the fifth,
A mold 50 as shown in FIG. 6 is prepared. The mold 50 is a split mold that is divided into an upper part and a lower part, which are separably joined together. Or, the set hole 5 has a diameter slightly smaller than the outer diameter of the outer ring 11 so that there is no problem in attaching and removing the outer ring 11.
3, and two grooves having the same width as the circumferential grooves 12 and 13 of the outer ring 11 and having a very small depth so as to face the respective circumferential grooves 12 and 13 of the outer ring 11 over the entire circumference along the circumferential surface of the set hole 53. circumferential grooves 54 and 55. A plate 56 is disposed on the upper surface of the upper mold 51 so as to be movable for mold release, and a runner 57 is formed so as to span the upper mold 51 and the plate 56, and the starting end of the runner 57 faces the injection nozzle N. The runner 58 is connected to the sprue 58 opening on the upper surface of the plate 56, and the terminal end of the runner 58 is connected to the circumferential grooves 54, 5 of the set hole 53.
The gates 59 and 60 are connected to gates 59 and 60, respectively, which open facing the gates 5.

The mold 50 configured in this way has an upper mold 51
and the lower die 52 are separated, and the outer ring 11 is assembled so that its circumferential grooves 12 and 13 are aligned with the circumferential grooves 5 in the set hole 53, respectively.
After the upper mold 51 and lower mold 52 are closed, the injection nozzle N is inserted into the sprue 58 of the mold 50 while heating the mold 50 to an appropriate temperature. Inject the molten synthetic resin. The molten synthetic resin passes through the sprue 58, the runner 57, and the gates 59, 60, and is filled into the circumferential grooves 12, 13 of the outer ring 11 and the circumferential grooves 54, 55 of the set hole 53. After filling, the upper mold 51 and the lower mold 5
2 and take out the outer ring 11. The above-described process was repeated to manufacture the outer ring 11 by injection molding the rings 14 and 15, and the bearing 1 was assembled using this outer ring 11.

By the way, in such a conventional method, mold 5
0 is configured as a split type, and its set hole 53
When inserting the outer ring 11 into the mold and removing the outer ring 11 from the set hole 53, it is necessary to separate the upper mold 51 and the lower mold 52 each time. In addition, it is difficult to maintain the initial mold accuracy because foreign matter is often caught between the joint surfaces, and the outer ring 11 of the bearing 1 is difficult to maintain.
The protruding heights of the rings 14 and 15 from the outer circumferential surface are uneven, and because of the split type, a lot of burrs are generated, resulting in an unsightly appearance. For this reason, conventionally, the ring 1 from the outer ring 11 surface
After setting the protrusion heights of rings 14 and 15 slightly higher than the required dimensions and injection molding the rings 14 and 15, finishing treatment is performed to remove burrs and shape the protrusion heights of rings 14 and 15 uniformly. However, it had drawbacks such as increased man-hours and higher manufacturing costs.

The present invention has been made in view of the above circumstances, and by using a special mold to form a synthetic resin ring that slightly protrudes from the outer circumferential surface of the outer ring in the circumferential groove, 2 for the synthetic resin ring after removing the outer ring from the mold
To provide a method for manufacturing a bearing that does not require any subsequent machining, can greatly reduce the number of man-hours, and can produce a beautiful finish with less occurrence of burrs, and a mold used for carrying out this method. .

A method for manufacturing a bearing according to the present invention is a method for manufacturing a bearing in which a synthetic resin ring for preventing creep is injection molded in a circumferential groove formed on the outer periphery of an outer ring, the outer diameter of which is slightly larger than the outer diameter of the outer ring. A set hole in the outer ring having a diameter slightly larger than the outer diameter of the outer ring, a gate opening in the circumferential surface of the set hole to face the circumferential groove of the outer ring, and a position of opening of the gate in the circumferential surface of the set hole. The groove is formed so as to face the circumferential groove of the outer ring over a majority of the circumferential direction thereof, with the position opposite to the gate opening position as the center, and gradually decreases from the position opposite to the gate opening position toward the gate opening position. The outer ring is inserted into the set hole in the integral mold having a circumferential groove with a very small depth, so that its circumferential groove faces the gate and the circumferential groove of the set hole, and the outer ring is inserted through the gate. It is characterized by injecting molten synthetic resin toward the circumferential groove.

The present invention will be specifically explained below based on drawings showing its implementation state.

FIG. 2 is a front view showing a mold (hereinafter referred to as the product of the present invention) used for carrying out the bearing manufacturing method according to the present invention (hereinafter referred to as the method of the present invention) with an outer ring inserted therein, and FIG. A vertical cross-sectional view taken along the - line in Figure 2,
FIG. 4 is an explanatory diagram of a set hole into which an outer ring is inserted in the product of the present invention. In the figure, reference numeral 11 denotes the outer ring of the bearing. Two grooves 12 and 13 (or one groove) of appropriate depth are formed in parallel on the outer periphery of the outer ring 11 over the entire circumference, and second and third grooves 12 and 13 are formed in parallel. As shown in the figure, it is inserted into the set hole 23 of the mold 2.

The mold 2 is constructed in one piece, and has a set hole 23 in the center that penetrates from one side to the other side, and a plate 2 that can be moved to release the mold in the upper part.
6 is disposed, and a runner 27 is formed so as to span this plate 3 and the mold 2.
The starting end of the runner 27 is connected to the sprue 28 opening at the center of the upper surface of the plate 3, and the terminal end of the runner 27 is connected to the set hole 23.
The gates 29 and 30 are connected to gates 29 and 30 that open on the peripheral surface of the gate. Gates 29 and 30 are grooves 12 and 1 of outer ring 11.
One piece is formed for each line of 3.

The diameter D ₂₃ of the set hole 23 is the outer diameter D ₁₁ of the outer ring 11.
It is set larger by the minute dimension Δd.
The larger this dimension Δd is, the easier it will be to insert or remove the outer ring 11 into the set hole 23, but on the other hand, there is a risk of burr generation. 11 Ring 14, 1 from the outer circumferential surface
5 protrusion height or outer ring 11 during injection molding
Set appropriately by considering the amount of deflection, etc. For example, when the protrusion height of the rings 14 and 15 from the outer peripheral surface of the outer ring 11 is set to 10 to 50 μm, it is desirable that Δd be approximately several μm. Grooves 24 and 25 are formed on the circumferential surface of the set hole 23 to face the circumferential grooves 12 and 13 of the outer ring 11 over the majority of the circumferential grooves 12 and 13 at a required distance in the axial direction. As shown in FIG. 4, the grooves 24 and 25 are arranged in the circumferential direction of the set hole 23 with the center O of the set hole 23 at a point symmetrical to the x position, which is the opening position of the gates 29 and 30, that is, the y position. The majority, in other words, the x position and y
Over a range beyond the positions on the circumferential surface of the set hole 23 that intersect with the horizontal line perpendicular to the line connecting the positions, that is, the z ₁ and z ₂ positions, the groove bottom surface is located at the center O of the set hole 23.
It is formed along a circle with a radius R centered on a point O' that is shifted by Δl toward the y position from the center. Each groove 2
The positions of the ends of the grooves 4 and 25, that is, the groove ends, are at the above-mentioned z ₁ and z ₂
It may be any position from the position to the x position, and may be appropriately designed depending on the rigidity of the outer ring 11, the injection pressure of the synthetic resin, etc.

The dimension from the inner circumferential surface of the set hole 23 to the groove bottom in each groove 24, 25, that is, the groove depth, is the ring 14 from the outer circumferential surface of the outer ring 11 at the y position.
The groove depth is set to Δb, which is approximately equal to the protrusion height of the groove 15, and is set to become gradually shallower from the y position toward the x position, and the groove depth is approximately zero at the groove end.

Note that the values of the radius of curvature R of the groove bottom surface of each of the grooves 24 and 25 mentioned above and the distance Δl between the center of curvature O' and the point O, etc. are determined when the synthetic resin is injected and filled, that is, when the outer ring 11 is under injection pressure. , the circumferential groove 1 of the outer ring 11
2, 13, the circumferential surface of the set hole 23, and the grooves 24, 25
The annular space formed between the two is appropriately set so as to have a uniform cross section over its entire circumference.

It goes without saying that the bottom surfaces of the grooves 24 and 25 in the set hole 23 may be formed by a combination of a plurality of circular arcs or along a circular arc.

Then, the outer ring 11 (or it may be assembled as a bearing) is inserted into the set hole 23 in the mold 2 as described above from one side, and the circumferential grooves 12 and 13 of the outer ring 11 are aligned with the grooves in the set hole 23. 24, 25
and positioned so as to face the gates 29 and 30. In this state, the diameter D ₂₃ of the set hole 23 is set slightly larger than the outer diameter D ₁₁ of the outer ring 11, so the outer circumferential surface of the outer ring 11 comes into contact with the set hole 23 at the y position, and from the y position The gap between the outer circumferential surface of the outer ring 11 and the circumferential surface of the set hole 23 gradually increases toward the x position, and the gap dimension is Δd at the x position.

While heating the mold 2 to an appropriate temperature, a synthetic resin such as 6-6 nylon is heated and melted to have an appropriate viscosity, and then injected from the injection nozzle N at high pressure.
The molten synthetic resin passes through the sprue 28, the runner 27, the gates 29, 30, and enters the circumferential grooves 12, 13 of the outer ring 11.
The circumferential surface of the set hole 23 and the groove 24 facing this,
During this time, the outer ring 11 is injected and filled into the annular space formed between the set hole 25 and the outer ring 11 due to the injection pressure.
It is in a state where it is strongly pressed against the y position side opposite to the position. As a result, the outer ring 11 is deflected, and the gap between the outer circumferential surface of the outer ring 11 and the circumferential surface of the set hole 23 at and near the x position becomes larger and approaches Δb. The distance between the surface and the bottom surface of the grooves 14, 15 or the circumferential surface of the set hole is made substantially uniform over the entire circumference of the outer ring 11, and the protruding heights of the rings 14, 15 are also made uniform.

Note that at the Z ₁ and Z ₂ positions, the gap between the inner circumferential surface of the set hole 23 and the outer circumferential surface of the outer ring 11 in the circumferential grooves 24 and 25 is slightly smaller than Δb;
Although the protrusion height of 15 is also slightly small at this position, it is not so large as to pose a practical problem.

Note that in the part of the set hole 23 where the grooves 24 and 25 are not provided, that is, at the X position or in the vicinity thereof including the X position, there is a gap between the outer circumferential surface of the outer ring 11 and the circumferential surface of the set hole 23 in the axial direction of the set hole 23. This means that there is no part that restricts the outflow of the molten synthetic resin, but this can be solved by changing the molding conditions. That is, the injection pressure is applied to deflect the outer ring 11 and bring the gap from Δd to Δb, which is slightly larger than this, and the injection pressure causes the outer ring 11 to try to protrude from the circumferential grooves 12 and 13 in the axial direction. The relationship between the surface tension of the molten synthetic resin and the gap Δb is expressed as follows:
The circumferential grooves 12 and 13 of the outer ring 11 and the grooves 24 and 25 of the set hole 23 are filled, and a protrusion corresponding to Δb is provided on the circumferential grooves 12 and 13 at the X position due to the deflection of the outer ring 11. The injection pressure, viscosity of the molten synthetic resin, injection amount, temperature, molding time, etc. are appropriately determined so that the molding is completed when the rings 14 and 15 are formed, thereby preventing the molten synthetic resin from flowing out in the axial direction. does not occur.

When the injection and filling of the resin is completed, if the outer ring 11 is pushed out in the axial direction of the set hole 23, the gate 2
The resin is cut at 9 and 30, and the outer ring 11 is removed from the set hole 23.

When the injection nozzle N is retreated, the plate 26 is released from the mold 2 together with the solid matter in the runner 27, and when the solid matter in the runner is blown away by air jet from an air nozzle (not shown), the plate 26 is released from the mold 2 together with the solid matter in the runner 27. 26 is returned to the mold 2, and the above-described operation is repeated again to remove the ring 1 from the outer ring 11.
Perform injection molding in steps 4 and 15.

The outer ring 11 with molded rings 14 and 15 is assembled as a bearing.

Next, specific molding conditions and molding results will be explained.

The inner diameter of the mold used is 32 mm, and the tolerance is +
It is 0.005/-0mm. Also, Δb=30μm, Δd=
It was set to 10 μm. In addition, the outer ring has an outer diameter of 32 mm and a tolerance of +0/
−0.011 mm was used. The mold was set at an angle of 80°, an outer ring at room temperature was fitted into the mold, and the same 6-6 nylon was injected from the sprue at an injection pressure of 65 to 70 kg/cm ² .

The amount of protrusion of the rings 14 and 15 made under these conditions from the outer circumferential surface of the outer ring is 10 to 30 μm at the Y position, 15 to 35 μm at the Z ₁ and Z ₂ positions, according to actual measurements of a large number of samples.
The range was 20 to 40 μm at the X position. This result was similar to the initial accuracy of the conventional product, demonstrating the effectiveness of the present invention. Note that under these molding conditions, substantially no outflow of the synthetic resin in the axial direction was observed.

As described above, in the present invention, the groove to be formed on the circumferential surface of the set hole in the mold is formed so as to face the circumferential groove of the outer ring, from the side opposite to the gate opening position to the side of the gate opening position. Since the injection molding of the synthetic resin ring is carried out using an integrated mold with grooves that gradually decrease in depth over the majority of the surface, even if the outer ring is deformed due to injection pressure, There is no variation in the protruding height of the ring, and it is extremely easy to insert and remove the outer ring from the set hole, resulting in high work efficiency.Moreover, since the mold is an integrated mold, it is easy to use when the mold is a split mold. As a result, there is no deterioration in mold accuracy due to wear of the abutment area between the upper and lower molds, or foreign matter gets caught between the upper and lower molds, and there is very little burr generation, which prevents secondary damage after ring molding. The present invention has excellent effects such as almost no processing required.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the configuration of a rolling bearing with a creep prevention function, Fig. 2 is a front view showing the product of the present invention used for carrying out the method of the present invention with an outer ring inserted, and Fig. 3 is a sectional view taken along the - line in Fig. 2, Fig. 4 is an explanatory diagram showing the relationship between the set hole and the groove in the product of the present invention, and Fig. 5 is a diagram showing the mold used in the conventional method with the outer ring inserted. FIG. 6 is a sectional view taken along the - line in FIG. 5. 4... Mold, 11... Outer ring, 12, 13... Circumferential groove, 14, 15... Ring, 23... Set hole,
24, 25... ditch, 29, 30... gate.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a bearing in which a synthetic resin ring for preventing creep is injection molded into a circumferential groove formed on the outer periphery of the outer ring, the outer diameter of which is slightly larger than the outer diameter of the outer ring. a set hole in the outer ring having a diameter slightly larger than the outer diameter of the set hole, a gate opening at a specific location on the circumferential surface of the set hole to face the circumferential groove of the outer ring, and the gate opening in the circumferential direction of the set hole. The groove is formed so as to face the circumferential groove of the outer ring over the majority of its circumferential direction with the center at the position opposite to the gate opening position, and gradually decreases from the position opposite to the gate opening position toward the gate opening position. The outer ring is inserted into the set hole of the integral mold having a groove formed to a very small depth so that its circumferential groove faces the gate and the groove of the set hole, and the outer ring is inserted from the gate. A method for manufacturing a bearing, characterized by injecting molten synthetic resin into a circumferential groove of an outer ring. 2 A mold used for manufacturing a bearing in which a synthetic resin ring for creep prevention, whose outer diameter is minutely larger than the outer diameter of the outer ring, is injection molded into a circumferential groove formed on the outer periphery of the outer ring, and is an integral type. and a set hole in the outer ring having a diameter slightly larger than the outer diameter of the outer ring, and a set hole for injection of molten synthetic resin opened at a specific location on the circumferential surface of the set hole to face the circumferential groove of the outer ring. The gate is formed to face the circumferential groove of the outer ring over a majority of the circumferential direction of the outer ring with the center located at a position on the circumferential surface of the set hole opposite to the gate opening position, and is opposite to the gate opening position. 1. A mold comprising: a groove having a minute depth that gradually decreases from the position toward the gate opening position.