KR101613592B1

KR101613592B1 - mold for bearing cage

Info

Publication number: KR101613592B1
Application number: KR1020150135179A
Authority: KR
Inventors: 고재영
Original assignee: 주식회사 우석엔프라
Priority date: 2015-09-24
Filing date: 2015-09-24
Publication date: 2016-04-21

Abstract

Disclosed in the present invention is a mold for forming a bearing cage comprising a first gate, a second gate, and an overflow gate installed in an arc form with uniform intervals. The injection mold smoothly discharges a residual gas generated in an inner cavity by installing auxiliary overflow gates on both sides of a ball core installed in the inner cavity between the first gate and the second gate.

Description

[MEANS FOR SOLVING PROBLEMS] A bearing cage molding die

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding a bearing cage, and more particularly, to a mold for molding a bearing cage which is capable of smoothly discharging residual gas and impurities of a molten resin during injection from a two- .

The bearing cage is a device in which a plurality of bearings are equally spaced and rotated. The ball bearing cage has ball pockets for the ball bearings to be mounted and rotated. When the spherical surface of the ball pocket is distorted or deviated from its center, If the flaws are formed, the rotation of the bearings is interrupted, the purpose of the desired bearings can not be achieved, and the service life of the bearings is shortened. The deformation of the ball pocket in the bearing cage is mainly caused by the residual gas ejected from the molding fluid at high temperature and high pressure during molding, and the inventors have made inventions in which such gas is smoothly discharged to the outside. Patent No. 0324218 (name of the invention: injection molding mold) (hereinafter referred to as the prior art) is an invention registered by the applicant of the present invention, in which an overflow gate is formed on the center line of two- And the remaining gas of the molten resin is discharged to the outside through the flow gate.

FIG. 1 is a cross-sectional view for explaining the overall structure of the prior art, and FIG. 2 is a cross-sectional view for explaining the positions of the balls cores and gates in FIG.

Fig. 1 is an explanatory drawing of an injection mold for forming a ball bearing cage, which is a kind of conventional bearing cage, in which a top core 10 and a mold main body 1 The upper core 10 is in contact with the mold surface of the lower core 20 to form the upper wall of the cavity 30 and the upper face 10 of the upper core 10 and the lower face 20 of the lower core 20, And a submarine type gate 50 for connecting the runner 40 and the cavity 30 to each other is formed. The movable lower core 20 is also provided with a first core 21 in which two-point gates 51 and 52 and an overflow gate 53 are formed. The first gate 51 and the second gate 52 formed on the first core 21 are connected to the left and right side walls C2 on the basis of any ball pocket with respect to the cage C formed in the cavity 30. [ And the overflow gate 53 is provided on the opposite side with respect to the imaginary intermediate point formed by the first gate 51 and the second gate 52. [ As shown in FIG. 2, seven ball cores 24 are provided, and seven ball pockets C1 formed in the cage C are formed. At this time, The angle formed by the first gate 51 and the second gate 52 is about 36.. In this way, the position where the molten resin enters through the first gate 51 and the second gate 52 is such that the waste portion of the cage C is avoided and the flesh is directed to the thick portion, Can be secured. Since the position of the overflow gate 53 corresponds to the point where the molten resin meets in the cavity 30, the impurities and the residual gas are reliably removed, and thus, a fatal product defect .

1 and 2, the lower core 20 forming the cavity 30 is integrally assembled on the movable side of the mold. The lower core 20 has two-point gates 51 and 52, A center core 22 integrally coupled to the center of the first core 21 to form a wall surface of the cavity 30, A second core 23 located under the core 21 and integrally coupled to the center core 22 and a second core 23 disposed around the second core 23 at a predetermined interval And a plurality of ball cores 24 inserted into the cage C to form a ball pocket C1 of the cage C. [

Since the entire lower core 20 forming the cavity 30 is integrally assembled on the movable side of the mold, the upper core 10 and the lower core 20 are not slidable during the molding operation, It does not.

As shown in the drawing, the prior art has a structure in which a disk-shaped anti-rotation core 25 is coupled to the lower center of a second core 23, in which seven ball cores 24 are arranged at regular intervals, The rotation of the ball core 24 is prevented by forming an arc surface 24a having the same center of curvature on one side of the lower end of the rotation preventing core 25 so as to be brought into close contact with the outer circumferential surface of the rotation preventing core 25. Meanwhile, the ball cores 24 are fitted to the second core 23, and then the inner and outer surfaces of the pocket-shaped portions 24b are curved in a curved surface to eliminate a machining error. The inner and outer surfaces of the pocket-like shaped portions 24b, which are formed into a curved surface, have the same center of curvature,

And coincides with the center point of the second core 23. The mold body of the prior art having such a structure is installed inside the mold for injection molding to be molded.

When the ball pockets are formed with a small number of balls in this way, two gates 51 and 52 are formed on both sides of a certain ball pocket, so that residual gas of the molten resin flowing along the cavity 30 A relatively large bearing cage having a large number of ball pockets can be formed in a relatively large space in the case of forming a gate on both sides of an arbitrary ball pocket, It takes a long time for the molten resin to reach the overflow gate 53 provided on the opposite side of the gates, so that the residual gas in the molten resin Is not ejected smoothly into the overflow gate, resulting in poor molding The.

Therefore, in order to solve such a problem, in a mold for molding a bearing cage having a plurality of ball pockets, three or more ball pockets are arranged between two gates 51 and 52, The impurities and the residual gas are smoothly discharged. However, the impurities and the residual gas in the path of flowing along the inner path of the gates are relatively long in the flow path of the resin, And residual gas can not be discharged, resulting in defective molding.

FIG. 3 is a diagram for explaining a configuration of a die that causes a molding failure in a two-point gate type molding die for producing a large-sized bearing cage according to the prior art.

3, the molten resin flowing along the runner 40 is press-fitted into the cavity 30 from the first gate 51 and the second gate 52 to form the first gate 51 and the overflow gate 53 1 outer cavity 511 between the first gate 51 and the second gate 52 and the second outer cavity 512 between the second gate 52 and the overflow gate 53, Lt; RTI ID = 0.0 > 513 < / RTI > 2, one ball core 24 is provided in the inner cavity 513 of the small-sized bearing cage mold. However, in the large-sized bearing cage mold, the first and second ball cores 24, And the second gates 51 and 52 are located, it takes a long time for the molten resin flowing out from the gates 51 and 52 to reach the overflow gate 53, A plurality of ball pockets are provided between the gate 51 and the gate 52 so that the gap between the first gate 51 and the second gate 52 is widened.

When a plurality of ball pockets are provided between the first gate 51 and the second gate 52, the remaining gas from the molten resin flowing through the first and second outer cavities 512 and 513 flows The remaining gas of the molten resin flowing along the inner cavity 513 flows out to the overflow gate 53. Therefore, there is no path for discharging the molten resin to the outside, resulting in distortion of the molded product, resulting in defective products.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a bearing cage molding die in which a plurality of ball pockets are provided between a gate and a gate forming a two- So that the residual gas generated from the molten resin is easily discharged to the outside.

Another object of the present invention is to provide a plurality of overflow gates in the inner cavity section so as to maintain the circularity of the ball pocket and prevent the distorted shape of the molded article.

Another object of the present invention is to improve the structure of the overflow gate so that the overflow gate of the inner cavity section can be installed in a narrow space between the runner and the inner cavity and the residual gas can be smoothly discharged.

According to an aspect of the present invention, there is provided a bearing apparatus comprising a fixed-side upper core and a movable-side lower core which are provided in a dividable manner, wherein a shape corresponding to the shape of a bearing cage having a plurality of ball pockets formed in the upper core and the lower core A submarine-type first gate and a second gate for communicating the molten resin from the runner to the molten resin to be injected from the runner, a virtual intermediate point between the first gate and the second gate Wherein an inner cavity between the first gate and the second gate, which is opposite to the overflow gate, is provided with an overflow gate provided on the opposite side to the ball pocket of the bearing cage, A plurality of ball cores are installed, wherein the inner cavity has at least one An overflow gate is provided on the secondary. The inclination angle formed by the center line and the vertical line of the auxiliary overflow gate is smaller than the inclination angle formed by the center line and the vertical line of the first gate and the second gate.

In the present invention, it is preferable that the first gate, the second gate and the overflow gate are provided on one arc and are provided at equal intervals.

According to an embodiment of the present invention, an odd number of ball pockets are provided in the inner cavity, and each of the auxiliary overflow gates is disposed on both sides of a ball pocket provided at the center of the inner cavity.

According to the present invention having the above-mentioned problems and solutions, the residual gas of the molten resin filled in the inner cavity between the first gate and the second gate can be smoothly discharged through the auxiliary overflow gate, As a result, smooth bearing motion can be created and the bearing life can be prolonged.

In addition, when the ball core is provided at the center of the inner cavity, the auxiliary overflow gate is provided on both sides of the ball core to prevent distortion that may occur on both sides of the ball core.

Also, the inclination angle of the auxiliary overflow gate can be securely set by making the inclination angle of the auxiliary overflow gate smaller than the inclination angle of the first and second gates and the overflow gate, and the gas can be discharged smoothly.

1 is a cross-sectional view for explaining the overall structure of the prior art.
Fig. 2 is a cross-sectional view for explaining the positions of the balls cores and gates in Fig. 1A.
FIG. 3 is a diagram for explaining a configuration of a die that causes a molding failure in a two-point gate type molding die for producing a large-sized bearing cage according to the prior art.
4 is a cross-sectional view for explaining an embodiment of the present invention.
Fig. 5 is a perspective view of the mold of the present invention. Fig.
FIG. 6A is a sectional view showing the inclination angles of the first and second gates of the present invention, and FIG. 6B is a sectional view showing the inclination angles of the first and second auxiliary overflow gates.

FIG. 4 is a cross-sectional view illustrating an embodiment of the present invention, and FIG. 5 is a perspective view of a mold of the present invention.

The number of ball cores (24) increases with the increase in the number of ball pockets of the bearing cage to smooth the flow of molten resin. As compared with the prior art, the number of ball cores (24) The operation and the basic structure of the upper and lower dies shown in Figs. 1 to 3 are similar to each other, and the same constituent elements are denoted by the same reference numerals, and a detailed description thereof will be omitted .

Also, as shown in FIG. 5, the bearing cage C ejected by the present invention exemplifies the formation of the ball pockets C1 on which 15 ball bearings can be mounted. However, the present invention is not limited thereto. The scope of protection of the product shall not be limited.

In the present invention, the movable lower core 20 which is in contact with the fixed side upper core 10 and the divided side PL and is movable relative to the upper core 10 includes a first gate 510 forming a two- A second gate 520 is provided and an overflow gate 53 is provided on the opposite side with respect to a virtual intermediate point formed by the first gate 510 and the second gate 520. At this time, The second gate 520 and the overflow gate 53 are provided on the concentric circles centering on the central point of the center core 22 and are provided at equal intervals on the circle. A ball core 24 having an arc surface 24a in close contact with the rotation preventing core 25 provided on the lower surface of the center core 22 and having an upper pocket- Five ball cores 24 are installed between the first gate 510 and the overflow gate 53 as shown in FIG. 4, and the second ball cores 24 are provided between the first gate 510 and the overflow gate 53, Five ball cores 24 are provided between the gate 520 and the overflow gate 53 and five ball cores 24 are provided between the first gate 510 and the second gate 520. [ Thus, the first gate 510, the second gate 520, and the overflow gate 53 are provided at equal intervals on a concentric circle. The cavity formed between the first gate 510 and the overflow gate 53 is referred to as a first outer cavity 511 and the cavity formed between the second gate 520 and the overflow gate 53 is referred to as a second outer side A cavity formed between the first gate 510 and the second gate 520, that is, an opposite cavity provided with the overflow gate 53 is referred to as a cavity 512, and the first and second inner cavities 513, (514), at least one auxiliary overflow gate is installed in the first and second inner cavities 513 and 514. A first auxiliary overflow gate (not shown) is formed on both sides of the ball core 24c disposed on the opposite side of the overflow gate 53, preferably at the center on the arc connecting the first gate 510 and the second gate 520, 531 and a second auxiliary overflow gate 541 are provided.

4, a ball core 24c is provided at a central position between the first gate 510 and the second gate 520 to form a center between the first gate 510 and the second gate 520, The auxiliary overflow gate can not be provided at the position of the ball core 24c and if the auxiliary overflow gate is provided only on one side of the ball core 24c, the injection shapes of both sides of the ball core 24c become unbalanced, It is preferable to install them one by one.

The angle between the center line and the vertical line of the first gate 510, the second gate 520 and the overflow gate 53 is set to be 45 degrees, but the auxiliary overflow gate 531 And 541 are installed between the runner 40 and the wall surface of the cavity 30 as shown in FIG.

FIG. 6A is a sectional view showing the inclination angles of the first and second gates of the present invention, and FIG. 6B is a sectional view showing the inclination angles of the first and second auxiliary overflow gates.

6A, a runner 40 is formed on the upper surface of the first core 21 and the runner 40 and the cavity 30 are connected to the first and second gates 510 and 520 So that the molten resin of the runner 40 is filled into the cavity 30 through the first and second gates 510 and 520. At this time, the inclination angle between the center line and the vertical line of the first and second gates 510 and 520 is 45 degrees. As shown in FIG. 6B, the first and second auxiliary overflow gates 531 and 541, which are provided for discharging the residual gas of the molten resin in the cavity 30 to the outside, are connected to the first core 21 The first and second gates 510 and 520 and the overflow gate 53 are formed to have a tilt angle of 20 to 40 degrees because they must be installed between the formed runner 40 and the sidewalls of the cavity 30 . At this time, if the angle of inclination of the auxiliary overflow gate is less than 20 degrees, the residual gas of the molten resin is prevented from being discharged to the outside, and a problem that the runner is damaged by more than 40 degrees occurs. The front end portions of the first and second auxiliary overflow gates 531 and 541 are connected to the side walls forming the inner cavities 513 and 514 and the rear end portion is formed with a discharge hole 550 The discharge hole 550 is installed inside the runner 40 formed as part of the arc as shown in Fig.

The diameter of the gate tip of each of the first and second auxiliary overflow gates 531 and 541 is preferably 1/4 to 1/2 of the diameter of the overflow gate 53. The overflow gate 53 discharges the remaining gas of the molten resin in the first and second outer cavity paths 511 and 512 to the outside, but the first and second auxiliary overflow gates 531 and 541, The residual gas of the molten resin in the inner cavity paths 513 and 514 is discharged to the outside so that its size does not exceed 1/2 of the diameter of the tip of the overflow gate. However, if it is less than 1/4, It is preferable that the flow function is reduced to 1/4 to 1/2.

If the number of the ball cores 24 provided in the inner cavity between the first gate 510 and the second gate 520 is an even number, the ball core 24 is not provided at the center of the inner cavity. In this case, It is preferable to provide one auxiliary overflow gate in the center of the inner cavity, and the length of the inner cavity is preferably half the length of the outer cavity, and the diameter of the inner cavity is preferably more than half of the outer cavity.

510: first gate 520: second gate
53; Overflow gate
511: first outside cavity 512: second outside cavity
531: first auxiliary overflow gate
541: second auxiliary overflow gate

Claims

A cavity formed in a shape corresponding to the shape of a bearing cage in which a plurality of ball pockets are formed in the upper core and the lower core and a molten resin A submarine-type first gate and a second gate for communicating the molten resin to be injected from the runner to the cavity through the runner, and a submarine-type first gate and a second gate for communicating the molten resin from the runner with the overflow provided on the opposite side with respect to a virtual intermediate point formed by the first gate and the second gate A bearing cage molding die having a gate, comprising:
A plurality of ball cores corresponding to the ball pockets of the bearing cage are provided in an inner cavity between the first gate and the second gate opposite to which the overflow gate is installed and the inner cavity is provided with at least one auxiliary overflow Gates are installed,
Wherein an inclination angle formed by a center line and a vertical line of the auxiliary overflow gate is smaller than an inclination angle formed by a center line and a vertical line of the first gate and the second gate.

The mold for forming a bearing cage according to claim 1, wherein the first gate, the second gate, and the overflow gate are provided on one arc and are provided at equal intervals.

The bearing cage mold of claim 1, wherein an odd number of ball pockets are provided in the inner cavity, and each of the auxiliary overflow gates is installed on both sides of a ball pocket provided at the center of the inner cavity.