JP6571988B2 - Steel ball retaining structure and steel ball press-fitting method - Google Patents

Description

  The present invention relates to a steel ball retaining structure and a method for press-fitting a steel ball that are accommodated in, for example, a solenoid of a solenoid valve and caulked to the tip of a plunger pin that opens and closes a flow path hole.

  2. Description of the Related Art Conventionally, electromagnetic valves have been used to control the supply of brake oil, for example, in automobile braking devices. Inside this electromagnetic valve is accommodated a plunger pin that is excited by a solenoid to open and close the flow path hole. The plunger pin is composed of a shaft body and a steel ball that is press-fitted into a caulking hole formed on a tip end surface thereof.

  As a structure for caulking the steel ball to the caulking hole, one shown in Patent Document 1 (Japanese Patent Laid-Open No. 58-104799) is known. In this structure, as a shape before caulking, the outer peripheral surface of the caulking hole is formed in a taper shape, and is configured to caulk a steel ball by caulking it from the outside.

JP 58-104799 A

  However, in the configuration in which the outer peripheral surface of the caulking hole is only tapered like the conventional caulking structure, the material does not flow uniformly to the surface of the steel ball, and there is a gap between the steel ball and the caulking hole. it can. For this reason, there was a problem that the steel balls could not be caulked with a desired supporting force, and the steel balls would wobble or come out of the caulking holes.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a steel ball retaining structure and a steel ball press-in method in which the supporting force of the steel ball attached by caulking is increased.

  In order to solve the above problems, a steel ball retaining structure according to the present invention includes a shaft body, a protrusion integrally formed on one end surface of the shaft body, a caulking hole provided in the protrusion, and a caulking hole. In a steel ball retaining structure comprising a steel ball that is press-fitted into a hole and caulked by caulking the outer peripheral surface of the protrusion, as a shape before caulking, the outer peripheral surface of the protrusion has a tip portion at the center axis. It is characterized in that it is formed of a straight surface that is parallel to the taper surface and a tapered surface that has a root portion that expands downward.

  Moreover, it is preferable that only the straight surface is caulked out of the straight surface and the tapered surface of the protrusion.

  Further, it is preferable that the straight surface of the protrusion is caulked so as to be equal to the inclination angle of the tapered surface.

  Moreover, it is preferable that the height of the straight surface and the taper surface of the protrusion is set to be substantially the same.

  In order to solve the above-described problem, the method of press-fitting a steel ball according to the present invention includes forming a protrusion integrally with one end surface of the shaft body, press-fitting the steel ball into a caulking hole provided in the protrusion, In the steel ball press-fitting method for caulking the steel ball by caulking the outer peripheral surface of the part, the tip part of the outer peripheral surface of the protrusion is formed on a straight surface parallel to the central axis, and the root part is on the lower side A steel ball is formed by crimping only the straight surface of the protrusion while pressing the lower half of the steel ball into the caulking hole and then pressing the upper half of the steel ball into the caulking hole. It is characterized by caulking.

  According to the steel ball retaining structure and the steel ball press-fitting method of the present invention, when the outer peripheral surface of the protrusion after caulking is tapered, the outer peripheral surface of the protrusion before caulking is not all tapered. , Make a part straight. When the steel ball is caulked by caulking the straight surface, the contact area between the steel ball and the fluidized material is increased, so that the supporting force of the steel ball is improved.

The partially cutaway perspective sectional view showing the retaining structure of the steel ball. The perspective view which shows the shape before crimping of a shaft body. The longitudinal cross-sectional view which shows the initial press-fitting process. The longitudinal cross-sectional view which shows the press-fit process of a middle period. The longitudinal cross-sectional view which shows the press-fit process of the last stage. The figure which shows the caulking shape when the opening angle (beta) of the caulking part of a metal mold | die is 90 degrees. The figure which shows the caulking shape when the opening angle (beta) of the caulking part of a metal mold | die is 75 degrees. The figure which shows the crimped shape when the opening angle (beta) of the crimping part of a metal mold | die is 60 degrees. The figure which shows the crimping shape when the ratio (gamma) of the height Hs of the straight surface with respect to the height H of a protrusion is 0.3. The figure which shows the crimping shape when the ratio (gamma) of the height Hs of the straight surface with respect to the height H of a protrusion is set to 0.4. The figure which shows the caulking shape when the ratio (gamma) of the height Hs of the straight surface with respect to the height H of a protrusion is 0.5.

  An embodiment embodying a steel ball retaining structure and a steel ball press-fitting method according to the present invention will be described with reference to FIGS.

  FIG. 1 shows a plunger pin 1. The plunger pin 1 is a valve that opens and closes a flow path hole (not shown) by being accommodated in a solenoid (not shown) of a solenoid valve (not shown), for example, and moved. The plunger pin 1 includes a shaft body 2, a protrusion 3 integrally formed on one end surface thereof, a caulking hole 3 a formed on the center line of the protrusion 3, and a press-fitting into the caulking hole 3 a. And a steel ball 4 that is caulked by caulking the outer peripheral surface.

  As shown in FIG. 2, the outer peripheral surface of the protrusion 3 has a straight surface 5 whose tip portion is parallel to the central axis and a tapered surface whose base portion expands downward as shown in FIG. 6 and so on. The opening angle α of the tapered surface 6 is set to 60 ° as shown in FIG.

  In addition, a slight depression 7 is formed in the center portion of the bottom surface of the caulking hole 3a. When the steel ball 4 is press-fitted into the caulking hole 3 by a method described in detail later, the steel ball 4 sinks here. It comes to include.

  2 to 4 are views showing a process for press-fitting the steel ball 4 into the caulking hole 3a and caulking the outer peripheral surface of the protrusion 3 by caulking. A general-purpose press machine (not shown) is used for press-fitting. A die 10 is attached to a portion that performs a vertical movement called a slide (not shown) of the press machine, and the shaft body 2 is installed at a position called a lower bolster (not shown).

  First, FIG. 3 shows an initial press-fitting step, in which a steel ball 4 is fitted into the caulking hole 3a. At this time, since the diameter of the steel ball 4 is set larger than the inner diameter of the caulking hole 3 a, at most, the lower half of the steel ball 4 is accommodated in the caulking hole 3.

  Next, FIG. 4 shows a mid-stage press-fitting process, in which a steel ball 4 is press-fitted into the caulking hole 3a. The press-fitting is performed by pressing the mold 10 from above the steel ball 4. The mold 10 has a fitting hole 11 formed on one end surface thereof, and is configured to be fitted to the protrusion 3 and the steel ball 4. The inner peripheral surface of the fitting hole 11 is formed from a tapered caulking portion 12 and a press-fit portion 13 formed by recessing the center of the bottom surface of the fitting hole 11. While pressing the press-fitting portion 13 against the upper part of the steel ball 4, the press-fitting is performed until the lower half of the steel ball 4 is accommodated in the caulking hole 3.

  Finally, FIG. 5 is a diagram showing a final press-fitting process, and shows a process of caulking the steel ball 4 by caulking the straight surface 5 of the protrusion 3. When the lower half of the steel ball 4 is press-fitted until it is accommodated in the caulking hole 3 a, the caulking portion 12 of the mold 10 comes into contact with the outer peripheral edge of the straight surface 5 of the protrusion 3. Furthermore, by pressing the mold 10 and pressing the upper half of the steel ball 4 into the caulking hole 3a, the caulking portion 12 caulks the outer peripheral edge of the straight surface 5 diagonally downward. The upper part is caulked with the caulking hole 3 exposed. Thus, by press-fitting the lower half of the steel ball 4 and then starting caulking, the contact area between the steel ball 4 and the fluid material increases, and a high support force can be obtained. Moreover, since the upper half of the steel ball 4 is pressed down firmly, the steel ball 4 can be supported stably.

  Further, in order to determine the optimum shape of the mold 10 for caulking, the opening angle β of the caulking portion 12 of the mold 10 shown in FIG. 3 is changed to three patterns of 90 °, 75 °, and 60 °, and FEM analysis is performed. A comparative experiment of caulking shape was performed using. As a result, as shown in FIG. 6, when the opening angle β is 90 °, the material does not flow toward the center, so that the supporting force for supporting the steel ball 4 cannot be obtained. As shown in FIG. 7, when the opening angle β is 75 °, material flow in the central direction is observed, but the boundary portion between the straight surface 5 and the taper surface 6 of the protrusion 3 protrudes. As shown in FIG. 8, when the opening angle β is 60 °, the material flows toward the center, and the straight surface 5 and the taper surface 6 of the protrusion 3 become a continuous flat surface. I can say that. If the opening angle β of the mold 10 is smaller than the opening angle α of the tapered surface 6 of the protrusion 3, the tapered surface 6 is pressed, so that the finished surface becomes rough or the material is excessive in the central direction. The problem of fluidity occurs. From the above results, it can be determined that the opening angle β of the mold 10 is preferably set to be the same as the opening angle α of the tapered surface 6 of the protrusion 3.

  Further, in order to determine the shape of the caulking hole optimum for caulking, the ratio γ (Hs / H) of the height Hs of the straight surface 5 to the height H of the protrusion 3 shown in FIG. The pattern was changed to 3 patterns of 4 and 0.5, and a caulking shape comparison experiment was performed using FEM analysis. As a result, as shown in FIG. 9, when γ = 0.3, the overall contact area between the steel ball 4 and the caulking hole 3a is small, and there is also a gap between the opening of the caulking hole 3a and the steel ball 4. It will occur. As shown in FIG. 10, when γ = 0.4, the contact area increases, but the gap remains. As shown in FIG. 11, when γ = 0.5, there is no gap and a sufficient contact area can be secured. When γ = 0.5 is exceeded, there is no gap and a sufficient contact area can be secured as in the case of γ = 0.5, but the material flows excessively near the bottom surface of the caulking hole 3a. Thus, the steel ball 4 cannot be stably supported. From the above results, it can be determined that it is preferable that the heights of the straight surface 5 and the tapered surface 6 of the protrusion 3 are set to be substantially the same.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Moreover, although the plunger pin 1 was mentioned as an example as a form which actualized this invention, it is also possible to implement to components other than this.

DESCRIPTION OF SYMBOLS 1 Plunger pin 2 Shaft body 3 Protrusion part 3a Caulking hole 4 Steel ball 5 Straight surface 6 Tapered surface 7 Depression 10 Mold 11 Fitting hole 12 Caulking part 13 Press-fit part

Claims (1)

In a steel ball press-fitting method in which a protrusion is integrally formed on one end surface of a shaft body, a steel ball is press-fitted into a caulking hole provided in the protrusion, and the outer peripheral surface of the protrusion is caulked. ,
The tip of the outer peripheral surface of the protrusion is formed as a straight surface parallel to the central axis, and the base is formed into a tapered surface that expands downward, and the lower half of the steel ball is press-fitted into the caulking hole. And then pressing the upper half of the steel ball into the caulking hole, and caulking the steel ball by caulking only the straight surface of the protrusion .