JP2009172732A - Impact rotary tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent the generation of vibration and noise in a cam mechanism by preventing the breakage of an elastic body in an impact rotary tool. <P>SOLUTION: This impact rotary tool 1 is provided with a driving shaft 12 having a motor 2 as power, an anvil 13 to which the rotation of the driving shaft 12 is outputted, a hammer 14 for striking the anvil 13, the cam mechanism 15 for making the hammer 14 perform an operation to strike the anvil 13 and a hammer spring 16 for energizing the hammer 14 toward the anvil 13 side. A metal plate 40 for limiting a retreating amount of the hammer 14 is provided via the elastic body 41 so that noise and vibration may not be generated due to a collision of steel balls 36, 36 against rear end walls of shaft cam grooves 34, 34 of the driving shaft 12, on a front side of a plate 38 on a rear end side of the hammer spring 16. The hammer spring 16 is set to regulate a deformation amount of an outer diameter of the elastic body 41, and the elastic body 41 functions as a regulating member to absorb an impact force and prevent the elastic body from being excessively compressed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an impact rotary tool such as an impact wrench or an impact driver used for tightening screws such as bolts and nuts.

  The impact rotary tool is a tool in which a hammer connected to a rotationally driven drive shaft strikes an anvil provided on the output shaft, so that a strong impact force is applied to the output shaft and the output shaft rotates. is there. The drive shaft and the hammer are connected to each other via a cam mechanism so as to be relatively rotatable and capable of moving forward and backward. A hammer spring is provided between the drive shaft and the hammer to urge the hammer toward the anvil. Yes.

By the way, the hammer moves forward by the spring force accumulated in the hammer spring, while the output shaft receives a reaction force from a target member such as a bolt, and the rotation of the output shaft is decelerated and the rotation of the hammer is delayed with respect to the drive shaft. Sometimes, the cam mechanism causes the hammer to retreat. In such a tool, when the hammer is retracted, a steel ball provided in the cam mechanism may collide with the end wall of the cam groove to generate noise and vibration. In order to prevent such noise and vibration from occurring, an impact rotary tool in which an elastic body that restricts the amount of retraction of the hammer is provided behind the hammer is known (for example, Patent Document 1 and Patent Document 2). reference).
JP 2002-46078 A JP-A-11-320432

  However, in the conventional tool as described above, when the rigidity of the target member is large or when screw galling occurs, a large reaction force acts on the hammer, and the hammer retreats vigorously to the elastic body. A large impact force is applied. Therefore, the elastic body may be broken, and the above vibration and noise cannot be reliably prevented.

  The present invention has been made to solve the above problem, and provides an impact rotary tool capable of preventing the occurrence of vibration and noise in the cam mechanism by preventing the elastic body from breaking. For the purpose.

  In order to achieve the above object, a first aspect of the present invention is directed to a drive shaft driven by a motor, an anvil that outputs rotation of the drive shaft, a hammer that strikes the anvil, and a hammer that strikes the anvil. In an impact rotary tool comprising a cam mechanism for performing an operation to be performed and a hammer spring that is compressed by retreating the hammer and biases the hammer toward the anvil, the hammer rotates relative to the drive shaft. An elastic body that alleviates an impact force that occurs when the hammer moves backward with respect to the drive shaft by the cam mechanism with a delay, and a regulating member that regulates the deformation amount of the outer diameter of the elastic body. Is.

  According to a second aspect of the present invention, in the first aspect of the present invention, the restricting member is configured to be a part of the hammer spring.

  According to a third aspect of the present invention, in the first aspect of the present invention, the regulating member is formed in a ring shape.

  According to the invention of claim 1, since the elastic body is restrained from increasing in the radial direction due to the impact force generated when the hammer is retracted, the elastic body is not excessively compressed, and the elastic body is damaged. Can be prevented. Therefore, the generation of vibration and noise in the cam mechanism can be reliably prevented, and the user can comfortably use the tool.

  According to the invention of claim 2, since the restricting member is configured to become a part of the hammer spring, when the elastic body increases in the radial direction and comes into contact with the restricting member, the elastic spring is compressed into the elastic spring. Therefore, a uniform force can be applied to prevent a decrease in durability of the elastic body due to scratches or partial stress.

  Similarly to the invention of claim 2, an impact rotary tool capable of preventing a decrease in durability of the elastic body is obtained.

(First embodiment)
An impact rotary tool according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 shows a schematic configuration of an impact rotary tool 1 according to the present embodiment. An impact rotating tool (hereinafter referred to as this tool) 1 includes a motor 2 that is a driving source, a striking mechanism unit 4 that is connected to the motor 2 and rotates a bit 3 attached to the tip with a striking force, and a motor 2. And a rechargeable battery 7 that is detachably attached to the main body cover 6. Here, the bit 3 has many types according to the types of screws such as bolts and nuts, and is detachably attached to the striking mechanism unit 4.

  The control circuit 5 supplies power from the rechargeable battery 7 to the motor 2 when the user pulls in a trigger switch 8 to be described later, and rotates the motor 2 at a rotation speed corresponding to the pull-in amount of the trigger switch 8. The main body cover 6 includes a housing portion 9 that accommodates the motor 2 and the striking mechanism portion 4 and a grip portion 10 that accommodates the control circuit 5 and is formed so as to be gripped by the user during operation. A trigger switch 8 for starting the motor 2 and adjusting its rotational speed is provided on the front surface of the grip portion 10.

  FIG. 2 shows an internal configuration of the striking mechanism unit 4. The striking mechanism unit 4 includes a drive shaft 12 connected via the motor 2 and the speed reducer 11, an anvil 13 that outputs rotation of the drive shaft 12, a hammer 14 that strikes the anvil 13, and an anvil 13 on the hammer 14. And a hammer spring 16 that urges the hammer 14 toward the anvil 13 side.

  The speed reducer 11 is disposed in front of the motor 2. The speed reducer 11 is a planetary gear mechanism, and includes a sun gear 18 that is a gear formed on the rotating shaft 17 of the motor 2, a plurality of planetary gears 19 and 19 that mesh with the sun gear 18, and planetary gears 19 and 19. It comprises a ring gear 20 that meshes with each other and a case 21 that accommodates each of the above parts. The sun gear 18 is inserted into a hole 22 formed in the center of the drive shaft 12. The planetary gears 19, 19 are arranged around the sun gear 18, and their centers are fixed by shafts 24, 24 inserted through a carrier 23 formed on the rear end side of the drive shaft 12. The ring gear 20 is fixed to the inner peripheral wall of the case 21, and the case 21 is fixed to the housing portion 9 of the main body cover 6. By configuring the reduction gear 11 as described above, the rotation of the motor 2 is decelerated at a predetermined reduction ratio determined by each gear and transmitted to the drive shaft 12.

  The drive shaft 12 includes the carrier 23 described above and a shaft portion 25 that passes through the center of the carrier 23. The shaft portion 25 is held at the rear end side by a bearing 26 fixed in the case 21 of the speed reducer 11, and the front end side is rotatably held by a rear hole 27 formed in the anvil 13.

  The anvil 13 is disposed in front of the hammer 14, and arm portions 28, 28 that engage with the hammer 14 when being hit by the hammer 14 are formed on the rear end side. The anvil 13 is held by a metal bearing 29 fixed to the front end side of the housing part 9 of the main body cover 6, and the front end side protrudes from the front end surface of the housing part 9. A bit insertion hole 30 for inserting the bit 3 is formed on the front end side of the anvil 13, and a chuck mechanism 31 for fixing the bit 3 inserted into the bit insertion hole 30 is provided.

  The hammer 14 has a through hole 32 in which the shaft portion 25 of the drive shaft 12 is loosely fitted at the center thereof, and is connected to the drive shaft 12 so as to be relatively rotatable and capable of moving forward and backward. The hammer 14 is biased toward the anvil 13 side by the restoring force of the hammer spring 16. On the front end side of the hammer 14, hammer claws 33, 33 that engage with the arm portions 28, 28 of the anvil 13 are formed radially.

  The cam mechanism 15 includes shaft cam grooves 34 and 34 formed in a spiral shape on the front outer peripheral surface of the shaft portion 25, hammer cam grooves 35 and 35 formed on the inner peripheral surface of the hammer 14, and a shaft cam groove 34. , 34 and the steel balls 36, 36 engaged with both the hammer cam grooves 35, 35. The shaft cam grooves 34 and 34 and the hammer cam grooves 35 and 35 are formed so that hemispheres of the steel balls 36 and 36 can enter, respectively, and the shaft cam grooves 34 and 34 and the hammer cam grooves 35 and 35 are overlapped. Steel balls 36, 36 are disposed in the space to be formed. By configuring the cam mechanism 15 as described above, the rotation of the drive shaft 12 is transmitted to the hammer 14 via the steel balls 36 and 36.

  The hammer spring 16 is inserted in the central space 37 through the shaft portion 25 of the drive shaft 12 and is compressed between the carrier 23 portion of the drive shaft 12 and the hammer 14. The hammer spring 16 is held by a plate 38 whose rear end side is fixed to the carrier 23, and is held by a plate 39 whose front end side is fixed to the hammer 14.

  In front of the plate 38 on the rear end side of the hammer spring 16, when the hammer 14 is retracted with respect to the drive shaft 12, the steel balls 36, 36 are rear end portions of the shaft cam grooves 34, 34 of the drive shaft 12. A metal plate 40 for limiting the amount of retraction of the hammer 14 is provided via an elastic body 41 so that noise and vibration are not generated by colliding with a wall (not shown). The elastic body 41 is for alleviating the impact force generated when the metal plate 40 and the hammer 14 come into contact with each other. The metal plate 40 and the elastic body 41 are formed in a ring shape so that the shaft portion 25 is inserted and positioned in the space 37 of the hammer spring 16. Here, the above-described hammer spring 16 is set so that the inner diameter thereof regulates the deformation amount of the outer diameter of the elastic body 41, and the elastic body 41 absorbs the above-described impact force and is compressed excessively. It functions as a regulating member to prevent.

  Next, operation | movement of the striking mechanism part 4 in the impact rotary tool 1 comprised as mentioned above is demonstrated. 3 (a) and 3 (b) show the operating state of the striking mechanism 4, wherein (a) shows the state where the hammer 14 has advanced to the maximum, and (b) shows the state where the hammer 14 has retracted to the maximum. Show.

  Before starting the tightening of the screw, as shown in FIG. 3A, the hammer 14 is urged toward the anvil 13 side by the restoring force of the hammer spring 16, and the hammer claws 33 and 33 of the hammer 14 and the anvil 13 The arm portions 28 are engaged. When the user pulls in the trigger switch 8 and starts tightening the screw, the motor 2 rotates. The rotation of the motor 2 is decelerated by the speed reducer 11 and output to the drive shaft 12, and the rotation of the drive shaft 12 is transmitted to the hammer 14 via the steel balls 36 and 36. At this time, since the hammer claws 33, 33 and the arm portions 28, 28 are engaged, the rotation of the hammer 14 is transmitted to the anvil 13, and the bit 3 attached to the anvil 13 rotates.

  Here, a case where the tightening torque of the screw is increased and a large load is applied to the anvil 13 will be described. In this case, the rotation of the anvil 13 is delayed, and accordingly, the rotation of the hammer 14 is delayed and is relatively delayed with respect to the rotation of the drive shaft 12. Then, the steel balls 36 and 36 are retracted from the front end walls of the shaft cam grooves 34 and 34, and the hammer 14 is retracted with respect to the drive shaft 12 while compressing the hammer spring 16. The arms 28, 28 are disengaged. Thereafter, the hammer 14 retreats to a position limited by the metal plate 40 and the elastic body 41 as shown in FIG. At this time, the steel balls 36 and 36 do not collide with the rear end walls of the shaft cam grooves 34 and 34 of the drive shaft 12. Here, when the hammer 14 comes into contact with the metal plate 40, the elastic body 41 is compressed in the axial direction and increases in the radial direction, and the outer peripheral surface thereof comes into contact with the inside of the compressed hammer spring 16.

  Thereafter, the steel balls 36 and 36 are moved forward along the shaft cam grooves 34 and 34 by the restoring force of the hammer spring 16, and the hammer 14 is moved forward with respect to the drive shaft 12. Then, the hammer claws 33, 33 of the hammer 14 and the arm portions 28, 28 of the anvil 13 are engaged again, and the anvil 13 is hit by the hammer 14 and a rotational force is applied to the anvil 13.

  As described above, according to the impact rotary tool 1 according to the present embodiment, the elastic body 41 is not excessively compressed when the hammer 14 moves backward with respect to the drive shaft 12 and comes into contact with the metal plate 40. Damage to the elastic body 41 can be prevented. Further, since a uniform force is applied to the elastic body 41 from the compressed hammer spring 16, it is possible to prevent the durability of the elastic body 41 from being deteriorated due to scratches or partial stress. Therefore, the generation of vibration and noise in the cam mechanism 15 can be reliably prevented, and the user can comfortably use the tool.

(Second Embodiment)
An impact rotary tool according to a second embodiment of the present invention will be described with reference to FIG. 4 and FIGS. 1 and 2 described above. 4 (a) and 4 (b) show the operating state of the striking mechanism 4 of the tool 1, (a) shows the state in which the hammer 14 has advanced to the maximum, and (b) shows the hammer 14 in the maximum retracted state. Shows the state. This tool 1 is the first in that instead of making the hammer spring 16 function as a restricting member, a restricting portion 42 for restricting the deformation amount of the outer diameter of the elastic body 41 is provided on the plate 38 on the rear end side of the hammer spring 16. It is different from the embodiment. The restricting portion 42 is formed so as to protrude forward from the front end surface of the plate 38. Other configurations are the same as those in FIGS. 1 and 2. Thereby, generation | occurrence | production of the vibration and noise in the cam mechanism 15 can be prevented reliably, and the user can use this tool comfortably.

(Third embodiment)
An impact rotary tool according to a third embodiment of the present invention will be described with reference to FIG. 5 and FIGS. 1 and 2 described above. 5 (a) and 5 (b) show the operating state of the striking mechanism 4 of the tool 1, (a) shows the state in which the hammer 14 has advanced to the maximum extent, and (b) shows that the hammer 14 has retracted to the maximum extent. Shows the state. This tool 1 is different from the other embodiments in that a restriction portion 42 that protrudes forward is provided on a carrier 23 that can hold the rear end side of the hammer spring 16. Other configurations are the same as those in FIGS. 1 and 2. Thereby, generation | occurrence | production of the vibration and noise in the cam mechanism 15 can be prevented reliably, and the user can use this tool comfortably.

  In addition, this invention is not restricted to the structure of the said various embodiment, A various deformation | transformation is possible in the range which does not change the meaning of invention. For example, the hammer spring 16, the plate 38, or a part of the carrier 23 has exemplified the configuration that regulates the deformation amount of the outer diameter of the elastic body 41, but a new separate part may be provided as a regulating member.

The side view which shows the impact rotary tool which concerns on the 1st Embodiment of this invention. Side surface sectional drawing which shows the impact mechanism part of the said impact rotary tool. (A) is side surface sectional drawing which shows the state which the hammer and the anvil engaged in the said impact mechanism part, (b) is side surface sectional drawing which shows the state which the hammer contact | abutted with the metal plate. (A) is side surface sectional drawing which shows the state which the hammer and the anvil engaged in the impact mechanism part of the impact rotary tool which concerns on the 2nd Embodiment of this invention, (b) is the state which the hammer contact | abutted with the metal plate Side surface sectional drawing which shows. (A) is side surface sectional drawing which shows the state which the hammer and the anvil engaged in the impact mechanism part of the impact rotary tool which concerns on the 3rd Embodiment of this invention, (b) is the state which the hammer contact | abutted with the metal plate Side surface sectional drawing which shows.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Impact rotary tool 2 Motor 8 Trigger switch 12 Drive shaft 13 Anvil 14 Hammer 15 Cam mechanism 16 Hammer spring (regulation member)
41 Elastic body

Claims (3)

A drive shaft driven by a motor; an anvil that outputs rotation of the drive shaft; a hammer that strikes the anvil; a cam mechanism that causes the hammer to strike the anvil; and the hammer retracts In the impact rotary tool provided with a hammer spring that is compressed by pressing and biasing the hammer toward the anvil side,
An elastic body that alleviates an impact force generated when the hammer moves backward with respect to the drive shaft by the cam mechanism with a delay in relative rotation of the hammer with respect to the drive shaft;
An impact rotary tool, further comprising a regulating member that regulates a deformation amount of the outer diameter of the elastic body.   The impact rotary tool according to claim 1, wherein the restriction member is configured to be a part of the hammer spring.   The impact rotary tool according to claim 1, wherein the restricting member is formed in a ring shape.

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