JPH0732006Y2 - Mold for forming rotary grindstone - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a mold for forming a rotary grindstone, and more specifically, a structure in which a metal hub can be securely attached to the center hole of the rotary grindstone. The present invention relates to a mold for forming a rotating grindstone.

[Prior Art] A mold for forming a rotary grindstone is a mold for press-molding a powdery raw material containing a binder to obtain a disk-shaped grindstone.

At the time of forming this grindstone, a metal hub is simultaneously fixed to a central hole formed in the center of the grindstone.

The conventional structure of this hub is shown in FIGS. 8 and 9.

That is, the reference numeral 1 in both figures is a hub, and the metal plate is formed in a ring shape, and the diameter of the center hole 2 of the hub is that of the center hole 4 of the rotary grindstone (hereinafter abbreviated as grindstone) 3. Slightly smaller than the diameter.

Triangular projecting pieces 5 are cut and raised downward from the hub 1 at equal angular intervals in the circumferential direction.

This hub 1 is pressed into the raw material when the grindstone 3 is formed,
It is integrated with the grinding wheel 3. The reason for providing the hub 1 is to prevent the peripheral edge of the center hole 4 from being damaged during mounting.

[Problems to be Solved by the Invention] When the above-described structure is adopted, the hub 1 is formed by only press-fitting several vertically downwardly projecting triangular projection pieces 5 into the grindstone. It has a problem that it easily comes off, and if the hub comes off, the vicinity of the center hole of the grindstone is easily damaged.

The present invention has been made in view of the above problems of the prior art. The object of the present invention is a rotary grindstone configured so that the hub can be integrated with the grindstone so that the hub does not come off. It is intended to provide a die for a board.

[Means for Solving the Problems] In order to achieve the above-mentioned object, according to the present invention, a core arranged to protrude in a central portion of a lower mold body by a spring while being pressed upward. A small diameter part is provided at the upper and lower ends of the gold, and a taper part continuous to this is formed, and a cylindrical protruding piece is formed on the entire circumference of the center hole of the ring-shaped hub, and the inner diameter of the center hole of the hub is formed. And the outer diameter of the small diameter part of the cored bar are almost the same.

[Operation] The hub is attached by fitting a cylindrical projecting piece on the outside of the small diameter part of the upper end of the core metal that is protruding upward from the lower mold body before molding, and the raw material is placed on the lower mold body. It is evenly distributed and the upper mold is fitted and pressed.

At this time, the core metal descends against the force of the spring, and when a pressing force is further applied, the cylindrical protruding piece is also pressed downward, and moves outward along the taper surface at the upper end of the core metal. It is curved, guided into the raw material of the grindstone, and pressed as it is to obtain a rotary grindstone.

At this time, since the tubular protrusion of the hub bites into the grindstone, it does not come off unless a considerably large external force is applied, and the periphery of the center hole is not damaged.

[Embodiment] Hereinafter, the details of the present invention will be described based on an embodiment shown in the drawings.

1 to 7 illustrate one embodiment of the present invention.
In the figure, the reference numeral 10 indicates the lower mold, and the lower mold
10 is assembled from a lower mold body 11 and an annular peripheral wall 12.
The lower die body 11 has a large diameter portion 11a and a small diameter portion 11b.
An annular peripheral wall 12 is slidably fitted in b.

The lower mold body 11 has a through hole 11c having a relatively large diameter that extends from the upper surface on the side of the small diameter portion 11b to the center of the wall thickness of the lower mold body 11 at the center thereof. It is continuous with a small diameter through hole 11d, and this through hole 11d is
There is an opening on the lower surface on the a side.

A cylindrical boss 13 having a trapezoidal cross section is provided at the inner rear end of the through hole 11c.
Are fitted, and a spring 14 is fitted on the outside thereof.

Then, a cored bar 15 is fitted in the through hole 11c so as to be able to move up and down, with its lower end in contact with the upper end of the spring 14. Therefore, the mandrel 15 is always given the habit of moving upward by the spring 14.

As shown in FIG. 3, the cored bar 15 is formed in a short cylindrical shape, and a small diameter portion 16 is formed at the upper and lower ends thereof, and a taper portion 17 is formed following the small diameter portion 16. There is.
In this way, the cored bar 15 is formed symmetrically in the vertical direction in order to use either the vertical direction of the cored bar 15.

On the other hand, the reference numeral 18 is a hub, which is formed of a metal plate in a ring shape, and a cylindrical projecting piece 19 is provided so as to protrude downward around the center hole.

The inner diameter of the protruding piece 19 is substantially the same as the outer diameter of the small diameter portion 16 of the cored bar 15. The height of the small diameter portion 16 is shorter than the height of the protruding piece 19.

On the other hand, the annular peripheral wall 12 has its lower surface side, that is, the large diameter portion 11
A counterbore 12a having a diameter larger than that of the large diameter portion 11a is formed on the side surface on the side where a is formed.

Further, through holes 11e are formed in the peripheral portion of the lower surface of the large-diameter portion 11a of the lower mold body 11 at equal angular intervals in the circumferential direction, and these through holes 11e have hexagonal holes at the head. The bolt 20 is fitted upward.

These bolts 20 penetrate the large diameter portion 11a and are screwed to the bottom surface of the counterbore portion 12a of the peripheral wall 12 arranged above.

A rubber ring 21 formed in a cylindrical shape is fitted to these bolts 20 between the upper surface of the large diameter portion 11a and the bottom surface of the spot facing portion 12a.

Further, between these bolts 20, circular concave portions 11f are formed on the upper surface of the large diameter portion 11a at equal angular intervals in the circumferential direction, and a coil is formed between the concave portions 11f and the bottom surface of the spot facing portion 12a. The spring 22 is cut off.

On the other hand, a tubular rubber ring 23 made of hard rubber, which is thin and has excellent wear resistance, heat resistance, and chemical resistance, is fixed to the inside of the peripheral wall 12 with an adhesive or the like.

In this way, the lower mold body 11 and the peripheral wall 12 are elastically coupled to each other, and the rubber ring body 23 is arranged so as to project from the upper surface of the small diameter portion 11b by a predetermined distance, and the upper surface of the small diameter portion 11b and the rubber ring body. twenty three
A circular concave portion 24 is formed by and the concave portion 24 is filled with the material 26 for the grinding stone.

Next, the operation of this embodiment configured as described above will be described.

First, the concave portion 24 is filled with a predetermined amount of the material 26, the upper mold 25 is lowered, and the upper surface of the material 26 is pressed with a predetermined pressing force. Due to this pressing force, the peripheral wall 12 and the rubber ring member 23 attached thereto move and descend toward the lower mold body 11 while bending the rubber ring 21 and the coil spring 22, and at the same time, the core metal 15 also bends the spring 14. It descends though it is not. In this way, a large constant pressing force is applied to the material 26, and the material 26 is press-molded with a predetermined density.

During this press molding, the elastic force applied to the peripheral wall 12 is
It is a combined elastic force of the rubber ring 21, coil spring 22 and spring 14, and it becomes a synergistic spring force that makes use of the characteristics of each material, and an extremely good spring force is obtained, which is ideal for press molding. As a result, the rotary grinder can be mass-produced with uniform quality. Further, the rubber ring body 23 mounted inside the peripheral wall 12 can prevent the small diameter portion 11b and the peripheral wall 12 from contacting and wearing. When the rubber ring 23 is pressed, the material 26
Although the pressure is applied by the rubber material, since it is made of rubber, it slightly dents due to the pressure, but since it is slight, the finished diameter of the product does not change significantly.

After molding, the small-diameter through hole 11 of the lower mold body 11 is formed.
From the d side, a pin (not shown) rises,
In order to press, the material 26 integrated with this is integrally projected from the recess 24, and the product is completed.

On the other hand, before the upper die 25 starts to press, the hub 18 has a cylindrical protruding piece 19 and a small diameter portion of the core metal 15 as shown in FIG.
Although it is fitted to the outer periphery of 16, when the pressing force begins to act, it descends along the tapered portion 17 and is spread outward. Then, the lower end of the protruding piece 19 is deformed so as to bite into the material 26 along the center hole of the grindstone to complete the molding of the grindstone.

In this state, the hub 18 completely covers the inside of the center hole of the grindstone, and the lower end of the protruding piece 19 and the hub are spread.
It does not come off because it is sandwiched between the horizontal parts of 18.

[Effect] As is apparent from the above description, according to the present invention, since the ring-shaped hub has a structure that can be fixed so as to wrap around the inner peripheral edge of the center hole of the grindstone, the hub can be fixed even if external force is applied. Does not fall out of the center hole of the grinding wheel. Therefore, the center hole does not come into contact with the shaft or the like and is not damaged.

[Brief description of drawings]

1 to 7 illustrate one embodiment of the present invention.
1 is an enlarged sectional view before pressing, FIG. 2 is an enlarged sectional view during pressing, FIG. 3 is a perspective view of a cored bar, FIG. 4 is a perspective view of a hub, FIG. 5 is a plan view, and FIG. 5 is a sectional view taken along the line AA in FIG. 5, FIG. 7 is a sectional view taken along the line BB in FIG. 5, FIGS. 8 and 9 are for explaining the conventional structure, and FIG. FIG. 9 is an enlarged sectional view of FIG. 9, and FIG. 9 is an enlarged plan view of the hub. 10 ... Lower mold, 11c, 11d ... Through hole 11 ... Lower mold body, 12 ... Peripheral wall 11a ... Large diameter part, 12a ... Counterbore part 11b ... Small diameter part, 14 ... Spring 15 ... Core bar, 23 ... Rubber ring 16 … Small diameter part, 24… Concave part 17… Tapered part, 25… Upper mold 18… Hub, 26… Material 19… Projection piece

Claims (1)

[Scope of utility model registration request] 1. A lower die body (11) having an annular peripheral wall (12) slidably fitted to the outer peripheral surface thereof, which is elastically supported at the central portion of the lower die body (11) and has a center hole of a rotary grinder. Along with forming the core 18, which has a core metal 15 for positioning the hub 18, a circular recess 24 having a predetermined depth is formed between the upper surface of the lower mold body 11 and the inner peripheral surface of the peripheral wall 12, and in the recess 24. Filling with the material 26 of the rotary grinder, the upper mold
In a rotary grindstone molding die that performs press forming by 25, a small diameter portion 16 and a taper portion 17 of a diverging end that is continuous with the small diameter portion 16 are formed at the upper and lower ends of a cored bar 15, and a hub 18 is formed downward along a center hole. To form a cylindrical protruding piece 19 facing, the inner diameter of this protruding piece 19 and the outer diameter of the small diameter portion 16 of the cored bar 15 are formed to be substantially equal,
Moreover, the small-diameter portion 16 is formed so that the height thereof is shorter than the height of the protruding piece 19, and a mold for forming a rotary grindstone.