JP2007276068A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool which is equipped with a protective cover for protecting a disc shape tip end tool, reduces the noise generated from the protective cover, and is safely and easily operated. <P>SOLUTION: The power tool is equipped with a fastening band 6 for mounting to an outer peripheral part of a cylindrical projection port 3, a semi circular fixing wall part 16a having an inner peripheral part fixed to the outer peripheral part of the band 6, internal capsule walls 15, 16 so as to form a semi circular cavity part 16b at the outer peripheral part of the semi circular fixing wall part 16a, and an opening part 19 for drawing the cover formed along the semi circular cavity part 16b in the internal capsule walls 15, 16. An inner peripheral end part 7b of the protective cover 7 is extended in the cavity part 16b formed by the internal capsule walls 15, 16 through the opening part 19 for drawing the cover, and the inner peripheral end part 7b is mounted so as to be sandwiched by an elastic body 18 in the cavity part 16b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power tool having a disc-shaped tip tool such as a portable disc grinder or a portable cutting machine, and more particularly to a power tool provided with a protective cover for protecting the disc-shaped tip tool.

  In a power tool having a disk-shaped tip tool such as a portable disk grinder or a portable cutting machine, a technique for attaching a protective cover for protecting the disk-shaped tip tool with a tightening band is well known. For example, Patent Document 1 below discloses a cover mounting mechanism using a tightening band for mounting a protective cover of a disc-shaped grindstone to a drive body of a disc grinder.

  An attachment mechanism according to the conventional technique disclosed in Patent Document 1 will be described with reference to FIG. The disc grinder transmits the motive power generated by the motor unit 51 to the output rotary shaft 58 by the gear transmission unit 52, and the motive power is applied to the disc-shaped grindstone 9 attached to the output rotary shaft 58 by using the mounting nut 11 and the washer 12. Tell. The disc-shaped grindstone 9 is a tip tool for grinding work, and the motor unit 51 to the output rotary shaft 58 serve as a driving device main body, and the protective cover 27 is a cylindrical cover mounting portion protruding from the gear transmission portion 52 by the fastening band 26. 3 is fixed. According to such a mounting mechanism of the protective cover 27, the manufacturing coast is low because of the relatively simple structure, and the tightening band 26 can be easily attached to the cover mounting portion 3 by operating the operation lever 5 of the tightening band 26. Can be fixed.

  However, in such a power tool, the vibration of the power mounting portion 3 is easily transmitted to the megaphone-shaped protective cover 27. The vibration source of this power tool is the grindstone 9 that performs the grinding operation, the gear transmission portion 52, and the like, and the vibration is transmitted to the protective cover 27 to generate noise. Since the protective cover 27 requires strength, a high-strength iron plate is used, and the vibration attenuation rate is small, so that the vibration is increased.

  As described above, a power tool having a disk-shaped tip tool such as a portable disk grinder is noisy during a metal grinding operation or a cutting operation of various materials, and gives an unpleasant feeling to the operator and surrounding people. The tip tool has been improved for this problem. For example, a cutting circular saw blade or a soft disc-shaped grindstone is commercially available with a slit to reduce noise generated from the tip tool itself.

  In addition, in the noise prevention technology of the disc grinder disclosed in Patent Document 2 below, a vibration absorbing member called packing is interposed at the attachment portion between the disc-shaped grindstone and the rotary output shaft, and further, a megaphone-shaped protective cover and the rotary shaft Noise is reduced by interposing a similar packing between the outer cylinder portions (cover attachment portions) that cover the cover.

JP-A-6-262517 Japanese Utility Model Publication No. 39-31638

  However, with the former noise prevention technology, noise generated from the tip tool itself can be reduced, but noise generated from other than the tip tool cannot be reduced. On the other hand, in the technique described in Patent Document 2, the protective cover is attached only by inserting a packing which is a vibration absorbing member. When a large load is applied to the protective cover, such as when the grindstone is broken, vibration absorption is performed. There was a problem that the member was easily damaged and the protective cover was easily removed. Further, in order to prevent the protective cover from being removed, if the packing is strongly pressed and the protective cover is firmly fixed, there is a disadvantage that the vibration absorption rate is small and noise is not reduced.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a power tool having a protective cover mounting mechanism with a simple configuration and less noise generation.

  Among the inventions disclosed in accordance with the present invention in order to solve the above problems, the characteristics of typical ones will be described as follows.

  According to one aspect of the present invention, the drive includes a case that surrounds the drive transmission unit, and a rotation output shaft that protrudes outside the case through a cylindrical protrusion provided at one end of the case. An apparatus body and an inner peripheral end portion that has an outermost peripheral end portion that covers at least a semicircular portion of an outer peripheral portion of a disc-shaped tip tool attached to the distal end portion of the rotary output shaft and is fixed to the cylindrical projecting port. A power tool having a protective cover and a mounting mechanism for fixing the protective cover to the cylindrical protruding port, the mounting mechanism including a band for mounting on an outer peripheral portion of the cylindrical protruding port, A semicircular fixed wall portion having an inner peripheral portion fixed to an outer peripheral portion, and the semicircular cavity portion together with the semicircular fixed wall portion at the outer peripheral portion of the semicircular fixed wall portion. An inner wall surrounding the outer periphery of the circular fixed wall, and the front A cover pull-out opening formed along the semicircular cavity in the inner wall, and the inner peripheral end of the protective cover passes through the cover pull-out opening. The inner peripheral end portion is attached so as to be sandwiched by the elastic body in the cavity portion.

  According to another feature of the invention, the inner peripheral end of the protective cover has a wide portion that extends into the cavity in a direction to close the opening for pulling out the cover.

  According to still another feature of the present invention, a gap between the cover drawing opening of the inner wall portion and the protective cover is smaller than a plate thickness of the inner peripheral end portion of the protective cover or the wide portion.

  According to the above-mentioned one feature of the present invention, the inner peripheral end portion side of the protective cover is extended into the hollow portion formed by the inner wall through the cover drawing opening, and the inner portion is formed in the hollow portion. Since the peripheral end portion is mounted so as to be sandwiched by the elastic body, the vibration of the power tool is blocked by the elastic body, and the vibration of the protective cover is reduced. Moreover, since the characteristic value of the elastic body can be set to an appropriate value, a power tool with less noise can be provided.

  According to the other feature of the present invention described above, the inner peripheral end portion of the protective cover has a wide portion extending into the cavity portion in the direction of closing the cover drawing opening, so that the protective cover falls off from the inner wall portion. Therefore, a safer power tool can be provided.

  According to still another feature of the present invention described above, the gap between the cover drawing opening of the inner wall portion and the protective cover is made smaller than the plate thickness of the inner peripheral end of the protective cover or the wide portion, Even if the protective cover is slightly deformed by the load on the protective cover, the end of the protective cover comes into contact with the inner wall portion, and the amount of deformation of the cover is suppressed.

  The above and other objects, and the above and other features and advantages of the present invention will become more apparent from the following description of the present specification and the accompanying drawings.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 5. In all the drawings for explaining the embodiments, members having the same function are denoted by the same reference numerals, and repeated description thereof is omitted. Further, members having the same functions as those of the above-described prior art will be described with the same reference numerals as those of the prior art.

  FIG. 1 shows an overall configuration diagram of a disc grinder according to an embodiment of the present invention. In FIG. 1, a disc grinder 100 includes a motor housing portion 51 containing a motor and made of, for example, a metal material, and a gear cover portion 52 made of, for example, a metal material connected to one end of the motor housing portion 51. A main body is provided. Further, the disc grinder 100 is connected to the other end side of the motor housing portion 51 and supplies a motor power switch 53 and a switch handle portion 54 for housing a motor control circuit board (not shown), and commercial AC power. Power cord 55.

  The motor (not shown) accommodated in the motor housing part 51 is comprised by the universal motor which can be started with AC power supply, for example. The power generated by the universal motor of the motor housing portion 51 is transmitted to a pair of bevel gears (not shown) mounted on the gear cover portion (drive transmission portion) 52, and the direction of the rotation shaft is changed by the pair of bevel gears. Then, it is transmitted to a spindle (rotation output shaft) 58. A disc-shaped grindstone 9, which is a tip tool, is attached to the tip portion of the rotation output shaft 58 by means of a mounting nut 11 and a washer 12 (see FIG. 2).

  The switch handle portion 54 is made of, for example, a plastic material case, and controls the motor in the motor housing portion 51 by turning on / off the power switch 53 in the switch handle portion 54 to thereby turn the disc-shaped grindstone 9 as a tip tool. Control the drive. An anti-vibration ring-shaped elastic body 56 is inserted into a connecting portion between the end of the motor housing portion 51 and the opposite end of the switch handle portion 54, and is switched from the driving device main bodies 51 and 52 or the tip tool 9. The vibration transmitted to the handle part 54 is reduced.

  The protective cover 7 is attached to the drive device body (51 and 52). An attachment structure for attaching the protective cover 7 to the drive device body will be described with reference to FIGS. FIG. 2 is an enlarged view showing the protective cover mounting mechanism shown in FIG. 3 is a top view of the protective cover mounting mechanism shown in FIG. 2 with the fastening band 6 and the protective cover 7 removed from the drive device main body, and FIG. 4 is a cross-sectional view taken along the line AB shown in FIG. FIG. 5 is a cross-sectional view taken along the line -C, and FIG.

  As shown in FIG. 2, the rotation output shaft 58 passes through the cylindrical protrusion (cover attachment portion) 3 of the cover 52 a of the gear cover portion 52 and protrudes to the outside of the cover 52 a. The protective cover 7 has an outermost peripheral end portion 7a that covers at least a semicircular portion (see FIG. 2) of the outer peripheral portion of a disk-shaped tip tool (disk-shaped grindstone) 9 attached to the distal end portion of the rotation output shaft 58, and a cylinder. It has an inner peripheral end 7b fixed to the projecting projection 3 and hangs down from the inner peripheral end 7b to the outermost peripheral end 7a so as to form a megaphone shape. As shown in FIGS. 3 and 5, the protective cover 7 has a substantially semicircular planar shape so as to protect almost half of the outer periphery of the disc-shaped grindstone 9, and is formed by, for example, squeezing an iron plate, The inner peripheral end portion 7b has wide portions 17a and 17b having a large width. An attachment mechanism for fixing the protective cover 7 to the cylindrical protrusion (cover attachment portion) 3 is configured as follows.

  That is, as shown in FIG. 4, a tightening band 6 for attaching to the outer peripheral portion of the cylindrical protrusion 3 (see FIG. 2), and a semicircular shape having an inner peripheral portion fixed to the outer peripheral portion of the tightening band 6. The semi-circular fixed wall 16a and the semicircular fixed wall 16a so as to form a cavity 16b having a semicircular cross-section in the circumferential direction together with the semi-circular fixed wall 16a on the outer periphery of the semi-circular fixed wall 16a. The upper inner wall portion 15 and the lower inner wall portion 16 surrounding the outer peripheral portion of 16a, and the cover drawing opening 19 formed along the semicircular cavity portion 16b in both the inner wall portions 15 and 16. Furthermore, the inner peripheral end 7b side of the protective cover 7 extends into the cavity 16b formed by the inner wall portions 15 and 16 via the cover drawing opening 19, and the inner peripheral end in the cavity 16b. 7 b is sandwiched between the elastic bodies 18. In the assembly example of the attachment mechanism, the fixed wall portion 16a of the lower inner wall member 16 is first welded to the outer peripheral portion of the fastening band 6, and then the inner peripheral end portion 7b of the protective cover 7 wrapped with the elastic body 18 is provided. The adhering wall portion 15a of the upper inner wall member 15 is welded adjacent to the upper portion of the lower inner wall member 16 and stored in the hollow portion 16b.

  As shown in FIGS. 3 and 4, the tightening band 6 includes a protrusion 10 that engages with the groove 3 a of the cylindrical protrusion (cover mounting portion) 3, and an inner diameter of the tightening band 6. An adjustment screw 20, a pin 22 that engages with the adjustment screw 20, and a pin 22 that supports the pin 22 so as to be movable in the circumferential direction of the fastening band 6 and is fixed to the fastening band 6. And an operation lever 5 (5A or 5B) that is supported inside the plate 21 and rotates around the pin 22. The operation lever 5 rotates about the pin 22 but is eccentric so that the distance between the contact surface of the plate 21 and the pin 22 changes according to the rotation angle. When the operating lever 5 is set to the position 5A indicated by the broken line, the cover mounting portion 3 and the fastening band 6 can be freely moved. Conversely, when the operation lever 5 is set to the position 5B indicated by the solid line, the cover mounting portion 3 and the fastening band 6 are provided. Is adjusted so that the distance between the adjusting screw 20 and the pin 22 is fixed.

  Further, as described above, the upper inner wall portion 15 and the lower inner wall portion 16 fixed to the outer peripheral portion of the fastening band 6 form a closed semicircular cavity portion 16b, and the semicircular cavity portion 16b. And a narrow cover drawing opening 19 penetrating from the outside to the outside. The inner peripheral end 7b side of the protective cover 7 extends into the hollow portion 16b formed by the inner wall portions 15 and 16 via the cover drawing opening 19, and is surrounded by the wide portions 17a and 17b of the protective cover 7. Is wrapped with an elastic body 18 and stored in the cavity 16b so as to be sandwiched between the upper inner wall 15 and the lower inner wall 16 described above.

  The elastic body 18 is made of a material that is softer and more resilient than iron, such as rubber or plastic. The softness and initial compression amount of the elastic body 18 are set to characteristic values suitable for vibration damping. These proper characteristic values can be easily set by measuring the vibration of the cover of the prototype and examining that the vibration has decreased.

  As shown in FIG. 5, the wide portion 17 on the inner peripheral end 7b side of the protective cover 7 has a structure in which, for example, portions 17a where the plate is bent upward and portions 17b where the plate is bent downward are alternately arranged. It is preferable to do. Thus, the load can be distributed to the upper and lower wide portions 17a and 17b with respect to the abnormal load applied to the protective cover 7. The upper and lower widths of the wide portions 17a and 17b are smaller than the cavity height in the cavity portion 16b formed by the upper inner wall portion 15 and the lower inner wall portion 16, and the upper inner wall portion 15 and the lower inner wall portion 16 form the cover. The protective cover 7 can be formed so as not to be detached from the cover drawing opening 19 by making the dimensions larger than the height of the drawing opening 19. The half ring-shaped end portions 16c and 16d along the circumferential direction of the hollow portion 16b formed by the upper inner wall portion 15 and the lower inner wall portion 16 are closed by plugs, and the protective cover 7 is slid out. There is no. As described above, the protective cover 7 is held with respect to the tightening band 6 via the elastic body 18. However, even if the elastic body 18 is damaged, the protective cover 7 does not come off the tightening band 6. Safety can be maintained as the protective cover 7 of the tip tool 9.

  The size of the opening of the cover drawing opening 19 (in the embodiment, the size in the height direction) is preferably slightly larger than the thickness of the protective cover 7 located in the opening. That is, the gap between the cover drawing opening 19 and the protective cover 7 may be small. For example, in order to prevent the protective cover 7 and the cover drawing opening 19 from coming into contact with each other when the protective cover 7 vibrates, a sufficiently low noise effect can be obtained with a gap of 1 mm or less. That is, the height of the cover drawing opening 19 of the inner wall portions 15 and 16 is set slightly larger than the thickness of the protective cover 7. On the other hand, for example, as shown in FIG. 4, when the protective cover 7 comes into contact with a workpiece or the like during work, the amount of deformation when a load in the E direction is generated is affected by the gap of the cover drawing opening 19. Since the amount of deformation of the protective cover 7 is small when the value of is small, the protective cover 7 is not greatly displaced from the outermost peripheral portion of the disc-shaped grindstone 9, so that a safe protective action can be secured.

  In the embodiment shown in FIG. 5, the wide portion 17 is formed by bending the same plate as the protective cover 7 upward and downward, but a separate member is provided on the inner peripheral end side of the protective cover 7 sandwiched in the hollow portion 16b. The plate of the protective cover may be locally thickened by fixing the plate. Further, when the breaking energy of the tip tool is small, even if the shape is bent to one side, it can sufficiently withstand an abnormal load as long as it is wider or thicker than the cover drawing opening 19.

  As will be apparent from the above description, according to the present invention, the inner peripheral end portion side of the protective cover extends into the cavity formed by the inner wall through the cover drawing opening, Since the inner peripheral end is mounted so as to be sandwiched by the elastic body, the vibration of the power tool is blocked by the elastic body and the vibration of the protective cover is reduced. Moreover, since the characteristic value of the elastic body can be set to an appropriate value, a power tool with less noise can be provided. Further, since the inner peripheral end of the protective cover has a wide part or a thick part extending into the hollow part in the direction of closing the cover drawing opening, the protective cover does not fall off from the inner wall part, and safer power can be obtained. Tools can be provided. Furthermore, the protective cover is slightly deformed by the load on the protective cover due to the structure in which the gap between the cover drawer opening on the inner wall and the protective cover is smaller than the plate thickness or wide part of the inner peripheral edge of the protective cover. Even so, since the end portion of the protective cover comes into contact with the inner wall portion and the amount of deformation of the cover is suppressed, the outer peripheral portion of the tip tool can be more safely protected.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. It is.

1 is an overall side view of a power tool according to an embodiment of the present invention. The partial expanded sectional view of the power tool shown in FIG. The top view about the protective cover attachment mechanism of the power tool shown in FIG. Sectional drawing which follows the ABC line of the top view of the protective cover attachment mechanism shown in FIG. The front view seen from the D direction of sectional drawing of the protective cover attachment mechanism shown in FIG. The partial expanded sectional view of the power tool which concerns on a prior art.

Explanation of symbols

3: Cylindrical protrusion (cover mounting portion) 3a: groove portion 4: bearing portion 5, 5A, 5B: operation lever 6: tightening band 7: protective cover 7a: outermost end of protective cover 7b: inside of protective cover Peripheral end 9: Disc-shaped grindstone 10: Band protrusion 11: Mounting nut 12: Washer 15: Upper inner wall 15a: Fixed wall 16: Lower inner wall 16a: Fixed wall 16b: Cavity 16c, 16d : End portions 17a, 17b of the hollow portion 18: Wide portion 18 of the protective cover 18: Elastic body 19: Cover drawing opening 20: Adjustment screw 21: Plate 22: Pin 51: Motor housing portion 52: Gear cover portion 52a: Cover 53: Power switch 54: Switch handle 55: Power cord 56: Ring-shaped elastic body 58: Rotation output shaft (spindle) 100: Power tool (disc grinder)

Claims (3)

A drive device body having a case surrounding the drive transmission portion, having a rotation output shaft that protrudes outside the case through a cylindrical protrusion provided at one end of the case, and a tip of the rotation output shaft A protective cover having an outermost peripheral end portion covering at least a semicircular portion of the outer peripheral portion of the disc-shaped tip tool attached to the portion, and having an inner peripheral end portion fixed to the cylindrical projecting port, and the protective cover A power tool having an attachment mechanism to be fixed to the cylindrical protrusion,
The attachment mechanism includes a band for attaching to the outer peripheral portion of the cylindrical protrusion, a semicircular fixed wall portion having an inner peripheral portion fixed to the outer peripheral portion of the band, and an outer peripheral portion of the semicircular fixed wall portion. An inner wall that surrounds an outer periphery of the semicircular fixing wall so as to form a semicircular cavity together with the semicircular fixing wall, and the semicircular cavity in the inner wall And a cover drawer opening formed along the
The inner peripheral end side of the protective cover extends into the cavity formed by the inner wall through the cover drawing opening, and the inner peripheral end is sandwiched by an elastic body in the cavity. A power tool characterized by being mounted so as to.   2. The power tool according to claim 1, wherein the inner peripheral end portion of the protective cover has a wide portion extending into the cavity portion in a direction of closing the cover drawing opening. The clearance gap between the said opening part for cover drawing | extracting of the said inner wall part and the said protective cover is smaller than the plate | board thickness of the said inner peripheral edge part of the said protective cover, or the said wide part, The Claim 1 or Claim 2 characterized by the above-mentioned. The power tool described in 1.

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