JP7514026B2 - Protective cover and grinder - Google Patents

Description

This invention relates to a protective cover that is attached to a grinder and a grinder with the protective cover attached.

Grinders equipped with a drive unit having a rotating shaft for mounting a disk-shaped tool tip such as a grindstone, and a housing for covering the drive unit, have been known for some time. In addition, a protective cover for covering the tool tip has also been attached to protect the user from the tool tip breaking and scattering (see, for example, Patent Document 1). As shown in FIG. 4, the protective cover 150 is usually attached to the cylindrical portion 132b of the housing 130 that surrounds the periphery of the rotating shaft 122. The protective cover 150 also includes a cover portion 160 that covers the rear (user side) of the tool tip 12, and a substantially annular band portion 170 for fastening and fixing the cover portion 160 to the cylindrical portion 132b.

JP 2001-88056 A

However, when a broken tool tip 12 hits the protective cover 150, the impact can cause the protective cover 150 to tilt (see dotted line in Figure 4). If the band portion 170 protrudes vertically from the cylindrical portion 132b, when the protective cover 150 tilts, the band portion 170 slides upward or downward over the corner 132c of the cylindrical portion 132b, causing the band portion 170 to come off the cylindrical portion 132b relatively easily.

The present invention aims to provide a protective cover that can prevent the cover from falling off the housing, and a grinder equipped with the protective cover.

The protective cover 50 of the present invention is a protective cover 50 that is attached to a grinder body 10 that includes a drive unit 20 having a rotating shaft 22 for mounting a tool tip 2, and a housing 30 that surrounds the rotating shaft 22 and has a cylindrical portion 32b for mounting the protective cover 50. The protective cover 50 includes a cover portion 60 that covers the rear of the tool tip 2, and a substantially annular band portion 70 for fastening and fixing the cover portion 60 to the cylindrical portion 32b. In the axial direction of the cylindrical portion 32b, the width W1 of the band portion 70 is smaller than the width W2 of the cylindrical portion 32b, and an upper cutout portion 72a is provided at the front upper portion of the band portion 70 so that both of the two corners 72c, 72c on the inner side of the band portion 70 abut against the outer surface of the cylindrical portion 32b.

In the protective cover 50, it is preferable that a lower cutout 72b is provided at the front lower part of the band portion 70.

The grinder 1 of the present invention comprises a drive unit 20 having a rotating shaft 22 for mounting the tip tool 2, a protective cover 50 for covering the tip tool 2, and a housing 30 having a cylindrical portion 32b surrounding the periphery of the rotating shaft 22 for mounting the protective cover 50. The protective cover 50 comprises a cover portion 60 for covering the rear of the tip tool 2 and a substantially annular band portion 70 for fastening and fixing the cover portion 60 to the cylindrical portion 32b. In the axial direction of the cylindrical portion 32b, the width W1 of the band portion 70 is smaller than the width W2 of the cylindrical portion 32b, and an upper cutout portion 72a is provided at the front upper portion of the band portion 70 so that both of the two corners 72c, 72c on the inner side of the band portion 70 abut against the outer surface of the cylindrical portion 32b.

In the above grinder 1, it is preferable that a lower cutout 72b is provided at the front lower part of the band portion 70.

It is also preferable that the cylindrical portion 32b protrudes forward further than the other portion connected to the cylindrical portion 32b, and a step 32c is formed between the other portion and the cylindrical portion 32b.

In the protective cover and grinder of the present invention, the width of the band portion is smaller than the width of the cylindrical portion in the axial direction, and an upper notch is provided at the front upper part of the band portion so that both corners on the inner side of the band portion abut the outer surface of the cylindrical portion. This prevents the band portion from protruding vertically from the cylindrical portion, and even if the band portion tilts due to a collision with the tip tool, the corners on the inner side of the band portion will catch on the outer surface of the cylindrical portion, preventing the protective cover from falling off the housing.

If a lower notch is provided at the front lower part of the band, it becomes easier to abut the two corners on the inner side of the band against the outer surface of the tubular part.

When the cylindrical portion protrudes forward further than the other parts connected to it and a step is formed between it and the other parts, finishing work such as dimensional adjustment and deburring of the cylindrical portion can be easily performed even when the housing is cast.

1 is a partially sectional side view showing a grinder according to an embodiment of the present invention. FIG. FIG. 4 is a cross-sectional view of a main part showing a state in which a protective cover is attached. FIG. 1 is a partially sectional side view showing a conventional grinder.

Next, one embodiment of the grinder of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the grinder 1 of the present invention comprises a grinder body 10 and a protective cover 50 attached to the grinder body 10.

The grinder body 10 includes a drive unit 20 and a housing 30 that houses the drive unit 20.

The drive unit 20 includes a motor 21 having an output shaft 21a, a rotating shaft 22 arranged at a predetermined angle (e.g., 90 degrees) relative to the output shaft 21a, and a gear unit 23 connecting the output shaft 21a and the rotating shaft 22.

The motor 21 is an air motor that rotates the output shaft using compressed air supplied from the outside. However, it is sufficient if it can rotate the output shaft 21a, and it may be, for example, an electric motor. The output shaft 21a is rotatably supported by a first bearing (ball bearing) 24.

The rotating shaft 22 is rotatably supported by a second bearing (ball bearing) 25. Reference numeral 26 denotes a bearing cover for fixing the second bearing 25 to the housing 30. As shown in FIG. 3, the bearing cover 26 has a through hole 26a through which the rotating shaft 22 passes in the center, and is screwed into a female screw 32d provided on the inner surface of the housing 30 with the rotating shaft 22 passing through the through hole 26a. A mounting fixture 27 for mounting a disk-shaped tip tool 2 such as a grindstone or a rotary blade is provided at the tip of the rotating shaft 22. The mounting fixture 27 has a receiving tool 27a that abuts on the upper surface of the tip tool 2, a holding tool 27b that abuts on the lower surface of the tip tool 2, and a fixing screw 27c that is screwed onto the rotating shaft 22 from below and fixes the receiving tool 27a and the holding tool 27b to the rotating shaft 22. The receiving tool 27a and the holding tool 27b are clamped by tightening the fixing screw 27c.

The gear section 23 consists of a first bevel gear 23a attached to the tip of the output shaft 21a and a second bevel gear 23b attached to the upper end of the rotating shaft 22, and is arranged so as to mesh with each other so as to transmit the rotation from the motor 21 to the rotating shaft 22.

The housing 30 includes a cylindrical main body 31 that extends in the front-rear direction along the output shaft 21a and mainly houses the motor 21, and a cylindrical bent portion 32 that bends downward from the front of the main body 31 and mainly houses the rotating shaft 22. This housing 30 is, for example, a casting, and the main body 31 and bent portion 32 are molded integrally from the beginning.

The lower end of the bent portion 32 is open, and the rotating shaft 22 protrudes downward from this opening 32a. The area near the edge of the opening is a cylindrical portion 32b for attaching a protective cover 50. This cylindrical portion 32b protrudes forward further than the other portion connected to the cylindrical portion 32b, and a step 32c is formed between the other portion. The inner peripheral surface of the cylindrical portion 32b is provided with a female thread 32d that screws into a male thread 26b provided on the outer peripheral surface of the bearing cover 26.

The protective cover 50 includes a cover portion 60 that covers the rear of the tool bit 2, and a substantially annular band portion 70 for fastening and fixing the cover portion 60 to the cylindrical portion 32b. It is made of a metal, such as steel.

The cover portion 60 is roughly semicircular in plan view and covers the top and side surfaces of the rear half of the tool tip 2.

The band portion 70 is generally annular in plan view. As shown in FIG. 2, the band portion 70 includes a rear band 71 that is arc-shaped in plan view and extends upward from the upper end of the cover portion 60, and a front band 72 that is arc-shaped in plan view and extends forward from one end of the arc of the rear band 71 and returns to the other end of the arc. The tip of the front band 72 is not in contact with the other end of the rear band 71, but is adjacent to it with a gap. The tip of the front band 72 and the other end of the rear band 71 are connected by a connector 80 consisting of a bolt 80a and a nut 80b, and the inner diameter of the band portion 70 can be changed by tightening the connector 80.

The front of the band portion 70, i.e., the front band 72, has an upper notch 72a at its upper part. Also, a lower notch 72b is provided at the lower part of the front band 72. The upper notch 72a and the lower notch 72b are provided over substantially the entire circumferential length of the front band 72. The width (band width) W1 of the front band 72 in the axial direction of the cylindrical portion 32b is smaller than the width W2 of the cylindrical portion 32b (see FIG. 3). The vertical cross-sectional shape of the front band 72 is a rectangle that is long in the vertical direction, and both of the two corners 72c, 72c on the inner side abut the outer surface of the cylindrical portion 32b.

The rear band 71 does not have an upper cutout. Therefore, the upper end surface 71a of the rear band 71 is located above the upper end surface 72d of the portion of the front band 72 where the upper cutout 72a is provided. The upper end surface 71a of the rear band 71 may be used to position the protective cover 50 in the vertical direction. In other words, the front band 72 may be designed so that when the upper end surface 71a of the rear band 71 abuts against the housing 30, both of the two corners 72c, 72c on the inner side of the front band 72 abut against the outer surface of the cylindrical portion 32b.

As described above, in the protective cover 50 configured as above, the two corners 72c, 72c on the inner side of the front band 72 both abut the outer surface of the cylindrical portion 32b. In other words, since the front band 72 does not protrude vertically from the cylindrical portion 32b, even if the tool tip 2 collides with the cover portion 60 and the band portion 70 tilts, the corners 72c will catch on the outer surface of the cylindrical portion 32b, preventing the protective cover 50 from falling off the housing 30.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, in the above embodiment, notches are provided at the top and bottom of the front band 72, but only the top, i.e., only the upper notch 72a, may be provided so that both corners 72c of the front band 72 abut the outer surface of the tubular portion 32c. In addition, the cover portion 60 and the band portion 70 are integrally formed, but they may be formed separately and integrated by assembling. In addition, the rear band 71 and the front band 72 may also be separate. For example, the rear band 71 and the front band 72 may be connected using two connectors 80. The vertical cross-sectional shape of the front band 72 is not limited to a rectangle, and various shapes such as a square, a polygon with pentagons or more, or a triangle may be adopted as long as they have two corners in the vertical direction.

The term "notch" does not only refer to a portion that has been actually cut out, but also includes a portion that has been cut out so that the upper end surface 72d of the front band 72 is lower than the upper end surface 71a of the rear band 71, and the lower end surface 72e of the front band 72 is higher than the lower end surface 71b of the rear band 71. Therefore, for example, a portion cut out in one step by pressing is also included in the "notch". The shape of the "notch" is not limited to a substantially rectangular shape as shown in FIG. 2, but may be a semi-elliptical shape, a semi-circular shape, a substantially U-shaped shape, or the like. It is preferable that the circumferential length of the upper cutout 72a and the lower cutout 72b is a length that can sufficiently secure the length at which the corner 72c abuts against the cylindrical portion 32b. For example, it is preferable that the circumferential length is 1/4 or more of the outer circumferential length of the cylindrical portion 32b, and more preferably 1/3 or more.

1 Grinder 2, 12 Tip tool 10 Grinder body 20 Drive unit 21 Motor 21a Output shaft 22, 122 Rotating shaft 23 Gear unit 23a First bevel gear 23b Second bevel gear 24 First bearing 25 Second bearing 26 Bearing cover 26a Through hole 26b Male screw 27 Mounting fixture 27a Receiver 27b Holder 27c Fixing screw 30, 130 Housing 31 Body unit 32 Bent portion 32a Opening 32b, 132b Cylindrical portion 132c Corner 32c Step 32d Female screw 50, 150 Protective cover 60, 160 Cover unit 70, 170 Band unit 71 Rear band 71a Upper end surface 71b Lower end surface 72 Front band 72a Upper notch 72b Lower notch 72c Corner 72d Upper end surface 72e Lower end surface 80 Connector 80a Bolt 80b Nut W1 Band width W2 Width of cylindrical portion

Claims (5)

A protective cover is attached to a grinder body including a drive unit having a rotary shaft for attaching a tool tip, and a housing having a cylindrical portion for covering the periphery of the rotary shaft and attaching the protective cover,
The tool has a cover portion that covers a rear of the tool bit, and a substantially annular band portion that extends upward from the cover portion and is fastened and fixed to the cylindrical portion,
A protective cover in which the width of the band portion is smaller than the width of the cylindrical portion in the axial direction, and an upper cutout portion is provided at the front upper portion of the band portion so that both of the two corners on the inner side of the band portion abut the outer surface of the cylindrical portion. A protective cover as described in claim 1, in which a lower cutout is provided at the front lower part of the band portion. A drive unit having a rotation shaft for mounting a tool tip;
A protective cover for covering the tip tool;
a housing having a cylindrical portion for covering the periphery of the rotating shaft and for attaching a protective cover;
the protective cover includes a cover portion that covers a rear of the tool bit, and a substantially annular band portion that extends upward from the cover portion and is fastened to the cylindrical portion;
In this grinder, the width of the band portion is smaller than the width of the cylindrical portion in the axial direction, and an upper notch is provided at the front upper part of the band portion so that both of the two corners on the inner side of the band portion abut against the outer surface of the cylindrical portion. A grinder as described in claim 3, in which a lower cutout is provided at the front lower part of the band portion. The grinder according to claim 3 or 4, wherein the cylindrical portion protrudes forward from the other portion connected to the cylindrical portion, and a step is formed between the cylindrical portion and the other portion.

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