JPH0217810Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a knife sharpening machine that sharpens cutlery such as knives using a whetstone driven by an electric motor to rotate at high speed, and has improved the structure for fixing the rotary whetstone to the motor shaft. It is something.

For this type of knife sharpening machine, the grindstone is approximately 5000 ~
It was rotated at a high speed of 8000 rpm, and during this rotation, the sharpening surface of the whetstone had to be attached to the bladed surface of the cutter at a fixed position, which caused a problem with the structure for attaching the whetstone to the motor shaft.

That is, in the past, when a grindstone was attached and fixed to the motor shaft of an electric motor, as shown in FIG. The shaft hole 17 of the bush 16 is formed into a straight blind round hole from the open end to the rear end, and the motor shaft end 21 with a larger diameter is inserted into the blind shaft hole 17. Press-fitted. However, in such a structure, since a sealed space 22 is formed between the inner end surface of the shaft hole 17 and the motor shaft end surface when they are fitted, it is not only difficult to press-fit the motor shaft end 21, but also the space 22
There is a risk that the grindstone 10 may be gradually pulled out from the motor shaft 6 due to the air pressure inside.

As an improvement measure, as shown by the two-dot chain line in FIG.
1 is press-fitted, the air in the shaft hole is allowed to escape to the outside through the escape hole 17a. With this type, it is easy to press-fit the motor shaft end 21, but the motor shaft end 21 may be press-fitted into the shaft hole 17 in an eccentric state, resulting in center runout when the grinding wheel 10 rotates. Another problem has arisen.

In any of the conventional examples described above, a press-fitting margin is provided between the motor shaft end portion 21 and the shaft hole 17 of the bushing 16, but the press-fitting margin tends to vary due to manufacturing reasons. Moreover, since the grinding wheel 10 is vulnerable to tension, the press-fitting allowance is smaller than the bush 16.
If the compressive deformation cannot be absorbed completely, the bushing 16 expands and a strong tensile stress acts between the abrasive grains of the grindstone 10. As a result, the grinding wheel 10 may crack or break.

This invention was proposed to solve this problem, and involves forming a blind shaft hole in an elastic bush provided at the shaft center of the grinding wheel, and forming a blind shaft hole in the shaft hole and the end of the motor shaft that fits into the shaft hole. By forming one of the two with a circular cross section and the other with a polygonal cross section that is inscribed or circumscribed in the circular cross section, it is possible to press fit without difficulty even if a sufficient press fit allowance is set for crimping. Moreover, when press-fitting, the air in the shaft hole can escape from the gap created during fitting.
The purpose of this is to enable the grindstone to be accurately attached and fixed to the motor shaft without center runout or coming off.

The details will be explained below based on the drawings.

Figures 2 to 6 show a first embodiment of the knife sharpening machine according to this invention, in which the main body case 1 is a synthetic resin molded product made of ABS resin or the like, and the lower case has a horizontally long rectangular shape. 2 and an upper case 3 with a gate-shaped transverse side surface that is joined to the upper case 2 in a lid-fitting manner, and a battery storage chamber 4 is formed in the left half of the main body case 1, and four battery cells are housed in this storage chamber. Type 2 dry batteries 5 are housed in a series-connected state.

An electric motor 6 is built in the center of the right half of the main body case 1, and the motor 6 and dry battery 5 are connected to a switch 7.
Continuously connected through.

This electric motor 6 has horizontal motor shafts 9 on the left and right,
9, and disk-shaped rotating grindstones 10, 10 are fixed to both motor shafts 9, 9, respectively, of which the left grindstone 10 is used for rough sharpening, and the right grindstone 10 is used for final sharpening. . A pair of symmetrical knife insertion guide grooves 13, 13 are arranged at positions facing each of the left and right side surfaces (knife sharpening surfaces) 12, 12 of these grindstones 10 for rough sharpening and finish sharpening,
By inserting a knife into either the left or right groove 13, either the left or right edged surface of the knife can be sharpened.

Now, insert the knife into the knife insertion guide groove 3, lightly touch the edged surface to the edge sharpening surface 12 of the whetstone 10, and pull the knife toward you at an appropriate speed with the switch 7 turned on. The blade can be sharpened sequentially from the base to the tip.

In addition, in order to prevent the switch 7 from being pressed by mistake when not in use, a gate-shaped erroneous operation prevention cover 14 is attached to the outer periphery of the main body case 1 so as to be slidable in the left-right direction. The grindstones 10, 10 and the switch 7 are brought together to expose them, and when not in use, the grindstones 10, 10 and the switch 7 are covered by being moved to the right side.

Figures 4 to 6 show the mounting and fixing structure of the grindstone and the motor shaft.The grindstone 10 is made by hardening abrasive grains with a binder and forming it into a disc shape, with a circular through hole in the center of the shaft. 15 is formed through the hole 15, and a bushing 16 is fitted and fixed in the through hole 15, and the blade sharpening surfaces 12, 12 are formed into conical convex surfaces so that the bladed surfaces of the blade are attached at an optimal angle. . Bushiyu 1
6 is a cylindrical molded product made of a synthetic resin such as polyacetal or nylon, or an elastic material such as hard rubber, and a blind shaft hole 17 opening toward the motor shaft 9 is bored in the shaft center thereof. This shaft hole 17 has a rear end surface 18 formed perpendicularly in the middle of the width direction of the bushing 16.
A peripheral side surface 20 having a regular hexagonal cross section parallel to the axial direction is provided between the inner end surface 18 and the opening surface 19.
is formed.

On the other hand, the motor shaft 9 is a solid metal shaft, and its tip 21 is formed in a circular cross section concentric with the rotational axis of the motor 6, and its diameter D is the distance between the opposing circumferential sides of the blind shaft hole 17. The diameter is made larger than d by the amount of press-fitting allowance, and the shaft end face is chamfered to facilitate fitting into the blind shaft hole 17.

To attach and fix the grindstone 10 to the motor shaft 9, the motor shaft end 21 is press-fitted into the blind shaft hole 17 of the bush 16. As the motor shaft end 21 is press-fitted into the blind shaft hole 17, a space 2 is formed between the inner end surface 18 of the shaft hole and the motor shaft end surface.
Air remaining in the shaft hole 2 escapes to the outside via the gap 23 formed between the shaft hole circumferential surface 20 and the circumferential surface of the motor shaft end 21, and when the fitting is completed, the air remains in the shaft hole inner end surface 18. and the end face of the motor shaft come into close contact. In FIG. 6, the shaft hole circumferential surface 20 presses into contact with the circumferential surface of the motor shaft end 21 at six locations, that is, at each position on the normal line of the shaft hole circumferential surface 20 passing through the motor axis, and these abutting portions The circumferential side surface 20 of the shaft hole is deformed in an arc shape along the circumferential surface of the shaft end portion 21, and the circumferential side surface portions of the shaft hole on both sides of the arc-shaped deformed portion 24 are deformed approximately tangentially from both ends of the deformed portion 24. As a whole, each ridge line of the circumferential side surface 20 of the shaft hole is moved inward in the axial direction compared to the state before press-fitting shown by the two-dot chain line in FIG. 6, and the bushing 16 is prevented from expanding and deforming toward the grindstone.

7 and 8 show a second embodiment of the present invention, in which the motor shaft end 21 is formed with a regular hexagonal cross section, and the blind shaft hole 17 of the bushing 16 is formed with a circular cross section. The length D of the diagonal line passing through the axis of the motor shaft end 21 is made larger than the diameter d of the blind shaft hole 17 by the press-fitting allowance. In this case as well, when the blind shaft hole 17 is press-fitted into the motor shaft end 21, the accumulated air in the space between the shaft hole inner end surface 18 and the motor shaft end surface is removed from the shaft hole circumferential surface 21 as in the previous embodiment.
0 and the circumferential surface of the motor shaft end to escape to the outside via the gap 23. At this time, the motor shaft end 21
The arcuate portion between the abutting portions of the circumferential side surface 20 of the shaft hole which is press-contacted to each edge of the shaft hole receives tension, and the radius of curvature increases compared to the state before insertion shown by the two-dot chain line in FIG. As a result, it is moved inward in the axial direction.

In the above embodiment, the cross-sectional shape of the shaft hole 17 of the bush 16 or the motor shaft end 21 is a regular hexagon, but in addition, each circumferential side surface or each ridge line is all pressed into contact with the inscribed circle or circumscribed circle. Even if it is formed into a polygonal cross section, the desired purpose can be achieved.

As explained above, in this invention, the shaft end 21
The blind shaft hole 1 of the bushing 16 made of an elastic material has a shaft diameter of
7, and the shaft end 21 or shaft hole 1
When the shaft end 21 is press-fitted into the blind shaft hole 17 by forming either one of them into a circular cross section and the other into a polygonal cross section, the inner peripheral surface of the blind shaft hole 17 and the shaft end are formed. A gap 23 parallel to the axial direction and having the same number of angles as the cross-sectional polygon is formed between the circumferential side surface of the cross-sectional polygon and the circumferential side surface of the cross-sectional polygon. Therefore, when the motor shaft end 21 is press-fitted into the shaft hole 17, the air accumulated in the space 22 between the shaft hole inner end surface 18 and the motor shaft end surface is released from the air gap 23 formed between the circumferential surfaces thereof. The motor shaft end 21 can be easily press-fitted into the shaft hole 17 with the motor shaft center aligned with the shaft center of the shaft hole 17, and the center runout of the grindstone 10 can be reliably prevented. After mating is complete, no high-pressure air remains in the shaft hole, so grinding wheel 1
0 will not come off unexpectedly from the motor shaft 9. Furthermore, when the bushing 16 is press-fitted, it deforms by the amount of press-fitting allowance, but this deformation strain narrows the gap 23 and shifts it inward in the axial direction, so there is almost no tension on the grinding wheel 10 itself. is not applied, and as a result, cracks occur in the grinding wheel 10,
It can effectively prevent cracking.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional front view of a main part showing a conventional example.
Figures 2 to 6 show a first embodiment of the knife sharpening machine according to this invention, in which Figure 2 is a perspective view, Figure 3 is a longitudinal sectional front view of main parts, and Figure 4 shows a grindstone and a motor shaft. FIG. 5 is an enlarged longitudinal sectional front view of main parts showing a state in which the grinding wheel and motor shaft are in the middle of being fitted together; FIG. 6 is a partially enlarged longitudinal sectional front view of FIG.
FIG. 7 and 8 show a second embodiment of the knife sharpening machine according to this invention, and FIG. 7 is a perspective view of the main part showing the bush and the motor shaft separated;
FIG. 8 is an enlarged vertical sectional side view of the main part showing the fitted state of the grindstone and the motor shaft. 1...Main body case, 6...Electric motor, 9...
Motor shaft, 10... Rotating grindstone, 13... Blade insertion guide groove, 15... Hole, 16... Bush, 17...
...Blind shaft hole, 18... Inner end surface of blind shaft hole, 20...
... Circumferential side of blind shaft hole, 21 ... Motor shaft end.

Claims (1)

[Scope of utility model registration request] In a knife sharpening machine equipped with an electric motor 6 and a rotary whetstone 10 driven by the motor 6, a blind shaft hole 17 of a bushing 16 made of an elastic material fitted and fixed to the center of the rotary whetstone 10, and the shaft Shaft end 21 of electric motor 6 having a shaft diameter larger than the inner diameter of hole 17
One of the two has a circular cross section and the other has a polygonal cross section, so that the shaft end 21 is connected to the inner peripheral surface of the blind shaft hole 17 and the peripheral surface of the shaft end 21 with respect to the blind shaft hole 17. A knife sharpening machine characterized in that the blade sharpener is press-fitted so as to form gaps 23 in the axial direction, the same number as the number of corners of the cross-sectional polygon.