JP2008284659A - Striking tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a striking tool which can reduce noise by absorbing vibration transmitted from spindle to anvil. <P>SOLUTION: The striking tool applies spinning hitting power to a bit 13 in such a way that a spinning hitting mechanism is attached to a spindle 8 driven in rotation by a motor, and that the spinning hitting power generated by the spinning hitting mechanism is intermittently transmitted to the bit (tip tool) 13 through from a hummer 9 to an anvil 3. Two segments 3A, and 3B are obtained by axially dividing the anvil 3 into two parts, and a rubber damper 12 (cushioning material) is interposed in an axial clearance between both segments 3A, and 3B. An elastic body 14 is interposed between the spindle 8 and the segment 3A at a side facing the spindle 8 of the anvil 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an impact tool for generating a rotating impact force and performing a required operation such as screw tightening, and more particularly to an impact tool that reduces noise.

  An impact tool as one form of an electric power tool is a tool that generates a rotating striking force using a motor as a driving source to rotate a tip tool, and intermittently imparts striking force to the tool to perform operations such as screw tightening. However, since it has features such as small recoil and high tightening ability, it is widely used at present. However, since the rotary impact mechanism that generates the rotational impact force is provided, noise during operation is large, and this noise is a problem.

  FIG. 5 shows a general impact tool conventionally used.

  FIG. 5 is a side sectional view of the impact tool. The impact tool shown in FIG. 5 is a tip tool by driving the rotary impact mechanism using the battery 1 as a power source and the motor 2 as a drive source, and applying rotation and impact to the anvil 3. The rotating impact force is intermittently transmitted to a certain bit to perform operations such as screw tightening.

  The motor 3 is housed in a body portion 4A of the housing 4, and power supply from the battery 1 to the motor 2 is turned on at an upper portion of the handle portion 4B integrally extending downward from the body portion 4A of the housing 4. A switch 5 is provided to turn off and start / stop the motor 2.

  Thus, in the rotary impact mechanism built in the hammer case 6, the rotation of the output shaft 2a of the motor 2 is decelerated through the planetary gear mechanism 7 and transmitted to the spindle 8, and the spindle 8 rotates at a predetermined speed. Driven. Here, the spindle 8 and the hammer 9 are connected by a cam mechanism, and this cam mechanism is formed on the V-shaped spindle cam groove 8 a formed on the outer peripheral surface of the spindle 8 and the inner peripheral surface of the hammer 9. Further, it is composed of a V-shaped hammer cam groove 9a and a ball 10 which engages with these cam grooves 8a, 9a.

  The hammer 9 is always urged by the spring 11 in the tip direction (to the right in FIG. 5), and at the time of restraining, the ball 15 and the cam grooves 8a, 9a are engaged with each other so that a gap is provided between the hammer 9 and the end face of the anvil 3. In the position. And the convex part not shown is symmetrically formed in two places on the rotation plane where the hammer 9 and the anvil 3 face each other.

  Thus, when the spindle 8 is rotationally driven as described above, the rotation is transmitted to the hammer 9 via the cam mechanism, and the protrusion of the hammer 9 is moved to the anvil 3 before the hammer 9 is rotated halfway. The anvil 3 is rotated by engaging with the convex portion of the shaft. When the relative reaction occurs between the spindle 8 and the hammer 9 due to the reaction force of the engagement, the hammer 9 moves along the spindle cam groove 8a of the cam mechanism. Then, while compressing the spring 11, the motor 2 starts to move backward.

  When the protrusion of the hammer 9 moves over the protrusion of the anvil 3 by the backward movement of the hammer 9 and the engagement between the two is released, the hammer 9 accumulates in the spring 11 in addition to the rotational force of the spindle 8. While being accelerated rapidly in the rotational direction and forward by the action of the elastic energy and the cam mechanism that has been moved, the spring 11 is moved forward by the biasing force of the spring 11, and the convex portion re-engages with the convex portion of the anvil 3 to rotate integrally. Begin to. At this time, since a strong rotational impact force is applied to the anvil 3, the rotational impact force is transmitted to the screw through the bit attached to the anvil 3.

  Thereafter, the same operation is repeated, and the rotational impact force is intermittently and repeatedly transmitted from the bit to the screw, and the screw is screwed into a member to be fastened such as wood.

  By the way, in the screw tightening work using such an impact tool, the hammer 9 also performs a back-and-forth motion simultaneously with the rotational motion. Therefore, these motions become a vibration source, and the fastened member is pivoted through the anvil 3, the bit and the screw. Excited in the direction generates a loud noise.

  Here, it is known that the noise energy from the fastening object accounts for a large proportion of the noise during work using the impact tool, and it is necessary to keep the excitation force transmitted to the fastening object small to reduce the noise. There are various countermeasures for this purpose.

  For example, Patent Document 1 proposes a configuration as shown in FIGS.

  That is, FIG. 6 is a side sectional view of the rotary impact mechanism portion of the impact tool proposed in Patent Document 1, and FIG. 7 is an enlarged detail view of a portion B in FIG. 6. In these drawings, those shown in FIG. The same symbols are assigned to the same elements.

  The illustrated impact tool is characterized in that a buffer mechanism is provided on the anvil 3. Here, the shock absorbing mechanism performs a shock absorbing function in the rotational direction and the axial direction, and directly transmits a rotational torque exceeding a set value. Specifically, the anvil 3 is divided into two in the axial direction. Thus, two divided pieces 3A and 3B are formed, and a rubber damper 12 as a cushioning material is provided in the axial gap between the two divided pieces 3A and 3B.

  By the way, although not shown, a plurality of (for example, two) claws are formed on the opposing end surfaces of the split pieces 3A and 3B of the anvil 3, and the claws of the split piece 3A and the claws of the split piece 3B are circumferential. Alternating in the direction. And the rubber damper 12 is arrange | positioned in the space formed between the nail | claws adjacent to the circumferential direction.

  Further, a bit 13 as a tip tool is detachably attached to the distal end portion of the split piece 3B of the anvil 3, and the convex portion 9b engaged with and disengaged from the convex portion 3a formed on the outer end surface of the split piece 3A is provided. The provided hammer 9 is always urged toward the anvil 3 side (front end direction) by a spring 11. The other structure is the same as that of the impact tool shown in FIG.

  In such an impact tool, in a no-load state where the rotational impact force does not act on the anvil 3, the split pieces 3A and 3B of the anvil 3 are not in direct contact with each other in the circumferential direction and the axial direction due to the presence of the rubber damper 12.

  Thus, when the spindle 8 is rotationally driven in the loaded state, the rotation is transmitted to the hammer 9 via the cam mechanism, and the hammer 9 has its projection 9b divided into 3A of the anvil 3 before half rotation. The divided piece 3A is rotated by engaging with the convex portion 3a.

  When relative rotation occurs between the hammer 9 and the spindle 8 due to the reaction force (engagement reaction force) associated with the engagement between the projection 9b of the hammer 9 and the projection 3a of the split piece 3A of the anvil 3, the hammer 9 9 starts to retract toward the motor 2 side (left side in FIGS. 6 and 7) while compressing the spring 11 along the spindle cam groove 8a of the cam mechanism.

  When the protrusion 9b of the hammer 9 moves over the protrusion 3a of the split piece 3A of the anvil 3 by the backward movement of the hammer 9 and the engagement between the two is released, the hammer 9 adds to the rotational force of the spindle 8; The elastic energy accumulated in the spring 11 and the cam mechanism rapidly accelerate in the rotational direction and forward while moving forward by the urging force of the spring 11, and the convex portion 9 b is the convex of the split piece 3 </ b> A of the anvil 3. Re-engage with the part 3a and start rotating the anvil 3. At this time, a strong rotational impact force is applied to the anvil 3, but the impact vibration is absorbed and attenuated by the elastic deformation of the rubber damper 12 by this rotational impact force, and the noise generated by the fastened member is kept low.

Further, when torque is applied to the anvil 3, the rubber damper 12 is elastically deformed and the split pieces 3A and 3B of the anvil 3 rotate relative to each other. However, while the torque is small, between the claws of the split pieces 3A and 3B of the anvil 3 Since a circumferential clearance is formed, torque is transmitted from one divided piece 3A to the other divided piece 3B via the rubber damper 12. When the torque increases beyond a certain value, the claws of the split pieces 3A and 3B of the anvil 3 come into direct contact (metal contact), and the torque passes from one split piece 3A to the other without passing through the rubber damper 12. Directly transmitted to the divided piece 3B. Therefore, noise reduction can be achieved without reducing the transmission torque.
JP 2006-289545 A

  By the way, as a transmission path of vibration due to the excitation force of the hammer 9 in the configuration shown in FIGS. 6 and 7, a path transmitted from the divided piece 3A of the anvil 3 to the bit 13 through the rubber damper 12 and the divided piece 3B, and a hammer 9 is a path that is transmitted from the divided piece 3A of the anvil 3 to the bit 13 via the spindle 8 through the rubber damper 12 and the divided piece 3B.

  6 and FIG. 7, the effect of reducing the vibration transmitted through the former path is obtained, but it is difficult to reduce the vibration transmitted through the latter path.

  Further, when the impact tool is assembled, the rubber damper 12 may be crushed in the axial direction depending on the dimensional tolerance, and the desired vibration reduction effect may not be obtained. Furthermore, since the pressing force of the rubber damper 12 during assembly varies depending on the operator, when the pressing force is large, the spindle 8 and the divided piece 3A of the anvil 3 are in direct contact (metal contact), and vibration is generated at the contact portion. There was also a problem that the noise was increased.

  The present invention has been made in view of the above problems, and an object thereof is to provide an impact tool capable of absorbing noise transmitted from a spindle to an anvil and reducing noise.

  In order to achieve the above object, according to the first aspect of the present invention, a rotary hammering mechanism is mounted on a spindle that is rotationally driven by a motor, and the rotary hammering force generated by the rotary hammering mechanism is intermittently applied to the tip tool from the hammer through the anvil. Is a tool that gives a rotational impact force to the tip tool by transmitting it in an axial direction, and the anvil is divided into two pieces in the axial direction, and a cushioning material is provided in the axial gap between the two divided pieces. In this impact tool, an elastic body is interposed between the spindle and the split piece on the side facing the spindle of the anvil.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the spring constant in the axial direction of the elastic body is set larger than the spring constant in the axial direction of the cushioning material.

  A third aspect of the invention is characterized in that, in the first or second aspect of the invention, the elastic body is constituted by a metal damper including a metal spring or rubber, an elastic resin and the like.

  According to the first aspect of the present invention, since the elastic body is interposed between the spindle and the divided piece of the anvil facing the spindle, the vibration transmitted from the hammer to the divided piece of the anvil via the spindle. Is absorbed by the elastic body, and the vibration transmitted to the tip tool and the accompanying noise are kept low.

  According to the second aspect of the present invention, since the spring constant in the axial direction of the elastic body is set larger than the spring constant in the axial direction of the cushioning material, the torque transmission positions of the hammer and the anvil do not change greatly, and Torque transmission is possible. In addition, the contact between the spindle and the anvil is prevented, the life of both is improved, the amount of expansion and contraction of the cushioning material in the axial direction is suppressed, and the cushioning material is prevented from deteriorating and its durability is enhanced. It is done.

  According to the invention described in claim 3, since the elastic body is constituted by the metal spring or the metal damper, the durability of the elastic body hit between the spindle and the anvil is enhanced.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 is a side sectional view of a rotary impact mechanism portion of an impact tool according to the present invention, FIG. 2 is an enlarged detail view of a portion A in FIG. 1, and FIGS. 3 and 4 are exploded perspective views of the rotary impact mechanism portion of the impact tool. is there.

  The impact tool according to the present embodiment is a cordless hand-held tool that uses a battery 1 as a power source and a motor 2 as a drive source, and the configuration of the impact tool is the conventional impact shown in FIGS. It is the same as that of the tool. Therefore, in the following description, the same elements as those shown in FIGS. 5 to 7 are denoted by the same reference numerals, and the description thereof will not be repeated.

  The impact tool according to the present embodiment is characterized in that a ring-shaped elastic body 14 is interposed between the spindle 8 and the divided piece 3A of the anvil 3.

  As shown in FIGS. 3 and 4, one divided piece 3A of the anvil 3 is formed in a substantially disc shape, and a circular hole 3b is formed at the center thereof. Further, as shown in FIG. 3, a linear convex portion 3a passing through the center is integrally formed on the end surface of the divided piece 3A on the hammer 9 side, and one end surface of the hammer 9 (facing the divided piece 3A). As shown in FIG. 4, two fan-shaped convex portions 9b are integrally formed at symmetrical positions separated by an angle of 180 ° in the circumferential direction, and are formed on these convex portions 9b and divided pieces 3A. The protruding portion 3a is intermittently engaged and disengaged every half rotation as described later.

  Further, as shown in FIG. 4, two claws 3c are integrally formed on the other end face of the split piece 3A (the end face facing the other split piece 3B) at symmetrical positions with an angle of 180 ° in the circumferential direction. ing. A circular hole 9 c is formed through the center of the hammer 9.

  As shown in FIGS. 3 and 4, the other divided piece 3B is formed by integrally forming a disk-like flange portion 3e in one end of a hollow shaft portion 3d in a direction perpendicular to the axis, and the flange portion 3e. As shown in FIG. 3, two claws 3f similar to the claws 3c on the divided piece 3A side are integrally formed at symmetrical positions separated by 180 ° in the circumferential direction on the end face (end face facing the divided piece 3A). ing.

  As shown in FIGS. 3 and 4, the rubber damper 12 is divided into two parts, and two columnar protrusions 12a are integrally projected on each divided piece. The rubber damper 12 is interposed between the split pieces 3A and 3B of the anvil 3 as shown in FIGS. Here, the two claws 3c and 3f formed on the opposing end surfaces of the split pieces 3A and 3B of the anvil 3 are alternately arranged in the circumferential direction, and the claw 3c and the claw 3f adjacent to each other in the circumferential direction are arranged. Each protrusion 12a of the rubber damper 12 is arranged in a space formed therebetween.

  Thus, as shown in FIG. 1, the anvil 3 is housed in the hammer case 6 so that the shaft portion 3 d of the divided piece 3 </ b> B is rotatably supported by the bearing metal 15. The other split piece 3A is assembled on the end surface of the portion 3e with the rubber damper 12 interposed therebetween so that the claws 3c and 3f are alternately arranged in the circumferential direction. The tip 8 of the spindle 8 inserted through a circular hole 3b formed at the center is supported so as to be capable of relative rotation and axial movement with respect to the divided piece 3A. A ring-shaped elastic body 14 is interposed between the spindle 8 and the divided piece 3 </ b> A of the anvil 3.

  Here, as the elastic body 14, a metal damper formed by sandwiching rubber or resin with a metal such as steel, a metal spring such as a wave washer having a spring property, a disc spring, or the like is used. This spring constant is set larger than the spring constant in the axial direction of the rubber damper 12.

  By the way, in the no-load state where the rotational impact force does not act on the anvil 3, a circumferential clearance is formed between the claws 3c and 3f of the two divided pieces 3A and 3B, and between the two divided pieces 3A and 3B. Is formed with an axial gap. Therefore, when no load is applied, the split pieces 3A and 3B of the anvil 3 are not in direct contact with either the circumferential direction or the axial direction.

  As shown in FIG. 1, a bit 13 is detachably attached to the shaft portion 3d of the split piece 3B of the anvil 3, and is engaged with and disengaged from the convex portion 3a formed on the outer end surface of the split piece 3A. The hammer 9 provided with the convex portion 9 b is constantly urged toward the anvil 3 side (front end direction) by the spring 11.

  Next, the operation of the impact tool having the above configuration will be described.

  In the rotary impact mechanism, the rotation of the output shaft (motor shaft) of the motor is decelerated through the planetary gear mechanism and transmitted to the spindle 8, and the spindle 8 is driven to rotate at a predetermined speed. Thus, when the spindle 8 is driven to rotate, the rotation is transmitted to the hammer 9 via the cam mechanism, and the hammer 9 has a convex portion 9b of the convex portion of the divided piece 3A of the anvil 3 before half rotation. The divided piece 3A is rotated by engaging with 3a.

  When relative rotation occurs between the hammer 9 and the spindle 8 due to the reaction force (engagement reaction force) associated with the engagement between the projection 9b of the hammer 9 and the projection 3a of the split piece 3A of the anvil 3, the hammer 9 9 starts to retract toward the motor side while compressing the spring 11 along the spindle cam groove 8a of the cam mechanism.

  When the protrusion 9b of the hammer 9 climbs over the protrusion 3a of the split piece 3A of the anvil 3 and the engagement between the two is released by the backward movement of the hammer 9, the hammer 9 adds to the rotational force of the spindle 8; The elastic energy accumulated in the spring 11 and the cam mechanism rapidly accelerate in the rotational direction and forward while moving forward by the urging force of the spring 11, and the convex portion 9 b is the convex of the split piece 3 </ b> A of the anvil 3. Re-engage with the part 3a and start rotating the anvil 3. At this time, a strong rotational impact force is applied to the anvil 3, and the anvil 3 is configured with a rubber damper 12 interposed between the two divided pieces 3A and 3B, and a shaft between the divided pieces 3A and 3B. Since the directional gap is formed, the impact vibration is absorbed and attenuated by the elastic deformation of the rubber damper 12 in the axial direction by the impact force.

  Further, since the elastic body 14 is interposed between the spindle 8 and the divided piece 3A of the anvil 3, vibration transmitted from the hammer 9 to the divided piece 3A of the anvil 3 via the spindle 8 is elastic. The vibration absorbed by the body 14 and transmitted to the bit 13 and the noise generated therewith are suppressed to a low level. In the present embodiment, since the spring constant in the axial direction of the elastic body 14 is set larger than the spring constant in the axial direction of the rubber damper 12, the torque transmission positions of the hammer 9 and the anvil 3 are not significantly changed, Torque transmission is possible. Further, the contact between the spindle 8 and the anvil 3 is prevented to improve the service life of the both, and the amount of expansion / contraction in the axial direction of the rubber damper 12 is suppressed to be small, so that the deterioration of the rubber damper 12 is prevented and its durability is improved. Is increased.

  Furthermore, in the present embodiment, since the elastic body 14 is formed of a metal spring or a metal damper, the durability of the elastic body 14 that is struck between the spindle 8 and the anvil 3 is enhanced.

  By the way, when a torque is applied to the anvil 3, the rubber damper 12 is elastically deformed and the two divided 3A and 3B pieces of the anvil 3 rotate relative to each other. However, while the torque is small, the claws 3c of the two divided pieces 3A and 3B of the anvil 3 Since a circumferential gap is formed between the claws 3f, torque is transmitted from the divided piece 3A to the divided piece 3B through the rubber damper 12. When the torque increases beyond a certain value, the claws 3c and the claws 3f of both the split pieces 3A and 3B of the anvil 3 are in direct contact (metal contact), so that the torque does not pass through the rubber damper 12 from the split piece 3A. Is transmitted directly to the segment 3B.

  Thereafter, the same operation is repeated, and the rotational impact force is intermittently and repeatedly transmitted from the bit 13 to the screw 16, and the screw 16 is screwed into a member to be fastened such as wood.

  INDUSTRIAL APPLICABILITY The present invention is particularly useful for reducing noise by applying it to impact tools such as hammer drills and impact drivers for generating a rotating striking force and performing required work.

It is a sectional side view of the rotation impact mechanism part of the impact tool which concerns on this invention. It is the A section enlarged detail drawing of FIG. It is a disassembled perspective view of the rotation impact mechanism part of the impact tool which concerns on this invention. It is a disassembled perspective view of the rotation impact mechanism part of the impact tool which concerns on this invention. It is a sectional side view of the conventional impact tool. It is a sectional side view of the rotation impact mechanism part of the conventional impact tool. It is the B section enlarged detail drawing of FIG.

Explanation of symbols

1 Battery 2 Motor 2a Motor output shaft (motor shaft)
3 anvils 3A, 3B anvil split piece 3a anvil convex portion 3b anvil circular hole 3c anvil claw 3d anvil shaft 3e anvil flange 3f anvil claw 4 housing 4A housing body 4B housing handle 5 Switch 6 Hammer case 7 Planetary gear mechanism 8 Spindle 8a Spindle cam groove 9 Hammer 9a Hammer cam groove 9b Hammer projection 9c Hammer hole 11 Spring 12 Rubber damper (buffer material)
12a Protrusion of rubber damper 13 Bit (tip tool)
14 Elastic body 15 Bearing metal 16 Screw

Claims (3)

A rotary striking mechanism is mounted on a spindle that is rotationally driven by a motor, and the rotational striking force generated by the rotary striking mechanism is intermittently transmitted from the hammer to the tip tool through the anvil, thereby giving the tip striking tool a rotational striking force. In the impact tool formed by dividing the anvil into two divided pieces in the axial direction into two divided pieces and interposing a cushioning material in the axial gap between the divided pieces,
An impact tool, characterized in that an elastic body is interposed between the spindle and the split piece on the side facing the spindle of the anvil.   2. The impact tool according to claim 1, wherein the spring constant in the axial direction of the elastic body is set larger than the spring constant in the axial direction of the cushioning material. The impact tool according to claim 1 or 2, wherein the elastic body is formed of a metal damper including a metal spring or rubber, an elastic resin, or the like.

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