JP6156785B2 - Impact tool - Google Patents

Description

The present invention relates to an impact tool that converts rotation of a motor into a rotational impact force and transmits it to a tip tool.

A hitting tool such as an impact driver or an impact wrench is known (for example, see Patent Document 1 below). This type of impact tool includes a spindle that is rotated by a rotational driving force from a motor, a hammer that is movably fitted in the direction of the rotation axis of the spindle, and an anvil that has a mounting portion on which a tip tool is mounted.

Cam grooves are provided on the inner peripheral surface of the hammer and the outer peripheral surface of the spindle, respectively, and the rotation of the spindle is transmitted to the hammer via steel balls inserted between these cam grooves. The hammer has a claw projecting on the anvil side of the spindle in the rotation axis direction and is urged in the anvil direction by a spring. The anvil is provided with a blade portion protruding in the radial direction of the spindle. When the rotation of the spindle is transmitted, the hammer moves forward in the anvil direction by the biasing of the spring while rotating. Then, the claw portion of the hammer collides with the blade portion of the anvil and meshes, and strikes in the rotation direction. Thereby, an anvil rotates with a front-end tool, and tightening work, such as a screw and a bolt, is performed.

After hitting the anvil, the hammer moves backward from the anvil while rotating against the urging force of the spring. Then, the claw portion of the hammer gets over the blade portion of the anvil, the meshing between the hammer and the anvil is released, and the hammer is detached from the anvil. Thereafter, the spring is urged to move forward again in the direction of the anvil while rotating, and the hammer strikes the anvil.

In such a striking tool, it is considered to increase the speed of the tightening operation by increasing the separation torque of the hammer and the anvil. Examples of a method for increasing the separation torque include increasing the spring constant of a spring that urges the hammer, and decreasing the lead angle of the cam groove provided in the spindle and the hammer.

JP 2003-94351 A

However, the spring constant of the spring has been set large in the past, and in order to increase it further, the spring constant can be further increased by using expensive materials and special shapes even if the spring size is small. Although it is possible, if you want to make it with cheap spring material, you must use a large spring. In this case, the overall length of the tool body becomes long, leading to an increase in size of the tool. In addition, in order to reduce the lead angle of the cam groove, the diameter of the spindle has to be increased, which also increases the size of the tool.

Therefore, there has been a demand for a striking tool capable of improving the fastening speed without increasing the size of the tool.

In order to solve the above-described problems, a striking tool according to the present invention has a motor, a hammer that is rotationally driven by the motor, and a mounting portion to which a tip tool is mounted, and the hammer hits the hammer in the rotation direction. The hammer has a striking surface that inclines in the rotational direction toward the tip tool side on the side in contact with the anvil in the rotational direction, and the anvil has a hammer in the rotational direction. It has a striking surface which inclines in the rotation direction toward the tip tool side on the side in contact with.

According to such a configuration, the force acting between the hammering surface and the hit surface of the anvil has a component in the direction from the hammer to the anvil, so that the separation torque of the hammer and the anvil increases. As a result, the time required for the hammer and the anvil to be engaged with each other is increased, so that the amount of torque transmitted from the hammer to the anvil increases. Therefore, it is possible to improve the fastening speed with the tip tool without increasing the size of the tool.

In the hitting tool described above, the hammer protrudes from the hammer main body portion toward the tip tool side and has a claw portion having a hitting surface, and the anvil has a blade portion having a hitting surface protruding in a radial direction from the anvil main body portion. It is preferable.

According to this configuration, the tightening speed can be improved without increasing the size of the tool with a simple configuration.

Further, it is preferable that the striking surface and the striking surface are inclined substantially parallel to each other.

According to such a configuration, torque can be transmitted effectively, so that the tightening speed can be improved.

The hammering tool according to the present invention includes a motor, a hammer main body, and a claw that protrudes forward from the hammer main body and has a striking surface. The hammer is rotated by the motor, and the front side of the hammer. A mounting portion provided on the front side to which the tip tool is mounted, and a blade portion provided on the rear side and having a hitting surface that protrudes in a radial direction from the anvil main body and contacts the hitting surface, An anvil that rotates in the direction of rotation of the hammer by striking the hammer, the angle formed by the front side of the hammer body and the striking surface is less than 90 °, and the front side of the anvil body The angle formed with the hit surface is configured to be greater than 90 °.

According to such a configuration, the force acting between the hammering surface and the hit surface of the anvil has a component in the direction from the hammer to the anvil, so that the separation torque of the hammer and the anvil increases. As a result, the time required for the hammer and the anvil to be engaged with each other is increased, so that the amount of torque transmitted from the hammer to the anvil increases. Therefore, it is possible to improve the fastening speed with the tip tool without increasing the size of the tool.

In the hitting tool described above, it is preferable that the hitting surface and the hit surface are inclined substantially parallel to each other.

According to such a configuration, torque can be transmitted effectively, so that the tightening speed can be improved.

According to the impact tool according to the present invention, it is possible to increase the tightening speed by increasing the separation torque of the hammer and the anvil without increasing the size of the tool.

It is a center sectional view showing the internal structure of the impact driver concerning an embodiment. It is a partial block diagram which shows the shape of the hammer and anvil in the impact driver which concerns on embodiment. (A) is a side view of a hammer, (b) is a side view of an anvil, and (c) is a side view showing engagement of a hammer and an anvil. Moreover, (d) is the figure which looked at (c) from the rotating shaft direction front side (lower side in a figure), (e) is the elements on larger scale in (c). It is a side view of the hammer in the impact driver which concerns on embodiment. It is a figure explaining the fastening operation | movement by the conventional impact driver. It is a figure explaining the fastening operation | movement by the impact driver which concerns on embodiment. It is a figure which shows the time change of the fastening torque and the anvil angle at the time of fastening operation | movement by the conventional impact driver and the impact driver which concerns on embodiment. (A) And (b) is a figure corresponding to the conventional impact driver, (c) And (d) is a figure corresponding to the impact driver which concerns on embodiment. It is a figure which shows the time change of the anvil angle at the time of the fastening operation | movement by the conventional impact driver. It is a figure which shows the time change of the anvil angle at the time of the fastening operation | movement by the impact driver which concerns on embodiment. It is a figure explaining the detail of the fastening operation | movement by the conventional impact driver and the impact driver which concerns on embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, the case where the present invention is applied to an impact driver will be described as an example.

First, an impact driver according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a central sectional view showing an internal structure of an impact driver 1 according to an embodiment. As shown in FIG. 1, the impact driver 1 includes a housing 2, a motor 3, a gear mechanism 4, a spindle 5, a hammer 6, an anvil 7, and an inverter circuit unit 8.

The housing 2 is made of resin and forms the outer shell of the impact driver 1, and includes a substantially cylindrical body portion 2a, a handle portion 2b extending from the body portion 2a, and a substrate housing portion 2c. . As shown in FIG. 1, a motor 3 is disposed in the body portion 2a such that its axial direction coincides with the longitudinal direction of the body portion 2a, and the gear mechanism 4, spindle 5, hammer 6 and anvil. 7 are arranged side by side toward one end side in the axial direction of the motor 3.

A metal hammer case 9 in which the hammer 6 and the anvil 7 are incorporated is disposed at the front side position in the body portion 2a. The hammer case 9 has a substantially funnel shape in which the diameter gradually decreases toward the front. An opening 9a is formed in the front end portion, and a tip portion of a tip tool mounting portion 72 described later is exposed from the opening 9a. An opening 72a is formed at the tip.

The handle portion 2b extends downward from a substantially central position in the front-rear direction of the body portion 2a, and a lower end thereof is connected to the substrate housing portion 2c. A switch mechanism 10 is built in the handle portion 2b. In the handle portion 2b, a trigger switch 11 which is an electronic switch serving as an operation location of the operator is provided at a front portion of the base portion from the trunk portion 2a. The trigger switch 11 is connected to the switch mechanism 10 and is used for switching between supply and interruption of drive power to the motor 3. Further, a forward / reverse selector switch 12 for switching the rotation direction of the motor 3 is provided at a connection portion between the handle portion 2b and the body portion 2a and immediately above the trigger switch 11.

The board accommodating portion 2c accommodates the control circuit portion 13 in the upper portion, and a battery pack mounting surface is formed in the lower portion. The board | substrate accommodating part 2c has comprised the shape which protrudes in the direction (front) which goes to the anvil 7 from the motor 3. As shown in FIG. The front end portion of the protruding portion is positioned so as not to protrude forward from the tip tool mounting portion 72, that is, positioned closer to the motor 3 than the tip tool mounting portion 72. Further, the width in the left-right direction of the substrate housing portion 2c is formed to be substantially equal to the width in the left-right direction of the body portion 2a. A battery pack 17 containing a plurality of battery cells such as lithium ion batteries is detachably mounted on the battery pack mounting surface.

The motor 3 is a brushless motor in the present embodiment, and includes a rotor including an output shaft and a plurality of permanent magnets, and a stator including a plurality of coils that are disposed at positions facing the rotor. (Illustrated). The output shaft of the motor 3 is disposed in the body portion 2a so that the axial direction coincides with the front-rear direction.

The gear mechanism 4 is disposed in front of the motor 3. The gear mechanism 4 is a speed reduction mechanism constituted by a planetary gear mechanism having a plurality of gears, and reduces the rotation of the output shaft and transmits it to the spindle 5.

The spindle 5 is disposed so as to be rotatable substantially coaxially with the output shaft of the motor 3, and cam grooves 5 a having a V-shape in a side view and a semicircular cross section are formed at two locations in the front circumferential direction. Steel balls 15 are respectively disposed in the pair of cam grooves 5a.

The hammer 6 includes a hammer main body portion 61 that is externally fitted to the spindle 5 and a pair of claw portions 62 that project from the front end of the hammer main body portion 61. The hammer 6 is biased forward by a spring 16 and is configured to be able to move backward against the biasing force. A cam groove 63 is formed on the inner peripheral surface of the hammer body 61, and the steel ball 15 is disposed between the cam groove 63 and the cam groove 5 a formed on the outer peripheral surface of the spindle 5. The rotation of the spindle 5 is transmitted to the hammer 6 through the steel ball 15.

The anvil 7 is disposed in front of the hammer 6 and includes an anvil body portion 71 and a tip tool mounting portion 72. An opening 72a is formed at the tip of the tip tool mounting portion 72, and a tip tool such as a bit is detachably mounted.

In addition, the anvil 7 is provided with a pair of blade portions 73 that are integrally formed with the anvil main body portion 71 at the rear of the tip tool mounting portion 72 and are disposed opposite to the rotation center of the anvil main body portion 71. . When the hammer 6 rotates, the one claw portion 62 and the one blade portion 73 collide with each other, and at the same time, the other claw portion 62 and the other blade portion 73 collide, and the hammer 6 and the anvil 7 are engaged with each other. Thereby, the blade portion 73 is hit and the rotational force of the hammer 6 is transmitted to the anvil 7. Further, after the collision between the claw portion 62 and the blade portion 73, the hammer 6 moves backward while rotating against the urging force of the spring 16. Then, when the claw portion 62 gets over the blade portion 73, the engagement between the hammer 6 and the anvil 7 is released, and the hammer 6 is detached from the anvil 7. Thereafter, the elastic energy stored in the spring 16 is released, the hammer 6 moves forward, and the claw portion 62 and the blade portion 73 collide again.

The inverter circuit unit 8 is provided with a switching element (not shown) such as a MOSFET (Metal Oxide Field Effect Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor).

Next, the shapes of the hammer 6 and the anvil 7 according to the present embodiment will be described in detail based on FIG. 2 and FIG. FIG. 2 is a partial configuration diagram showing shapes of the hammer 6 and the anvil 7 in the impact driver 1 according to the embodiment. 2A is a side view of the hammer 6, FIG. 2B is a side view of the anvil 7, and FIG. 2C is a side view showing the engagement of the hammer 6 and the anvil 7. FIG. 2D is a view of FIG. 2C viewed from the front side in the rotation axis direction (lower side in the drawing), and FIG. 2E is a partially enlarged view of FIG. 2C. FIG. 3 is a side view of the hammer 6 in the impact driver 1 according to the embodiment.

The hammer 6 has a cylindrical hammer body 61 fitted on the spindle 5, and can rotate substantially coaxially with the rotation axis of the spindle 5 and move in the direction of the rotation axis. The hammer body 61 is biased forward by the spring 16 as shown in FIG.

Moreover, the hammer 6 has a pair of nail | claw part 62 which protrudes in a rotating shaft direction from the hammer main-body part 61, as FIG. 2 (a) and FIG. 3 show. On both sides of the claw portion 62, planar hitting surfaces 62a and 62b are formed. When the motor 3 rotates forward, the hammer 6 rotates in the direction of arrow A shown in FIG. 2D (counterclockwise when viewed from the front in the rotation axis direction). The striking surface 62a is a surface that strikes one blade portion 73 of the anvil 7 during this rotation, that is, forward rotation. Further, when the motor 3 rotates in the reverse direction, the hammer 6 rotates in the direction opposite to the arrow A (clockwise as viewed from the front in the rotation axis direction). The striking surface 62b is a surface that strikes the other blade portion 73 of the anvil 7 during this rotation, that is, reverse rotation.

As shown in FIGS. 1 and 2B, the anvil 7 is disposed such that a cylindrical anvil main body 71 is rotatable substantially coaxially with the rotation axis of the spindle 5. A tip tool mounting portion 72 is provided at the front end in the rotational axis direction of the anvil main body 71 so as to be integrally rotatable with the anvil main body 71 substantially coaxially.

A pair of blade portions 73 projecting radially outward from the anvil main body 71 are provided on the rear side in the rotation axis direction of the anvil main body 71. On both sides of the blade portion 73, planar hitting surfaces 73a and 73b are formed. The hit surface 73a is a surface hit by the hit surface 62a of the one claw portion 62 of the hammer 6 when the anvil 7 rotates in the direction of arrow A shown in FIG. Is a surface to be struck by the striking surface 62b of the other claw 62 of the hammer 6 when the anvil 7 rotates in the reverse direction to the arrow A.

In the hammer 6 and the anvil 7, the striking surfaces 62a and 62b and the striking surfaces 73a and 73b each have an inclination with respect to the rotation axis direction. FIGS. 2C to 2E show the engagement of the claw portion 62 of the hammer 6 and the blade portion 73 of the anvil 7 during normal rotation. The striking surface 62a that strikes the anvil 7 during the forward rotation of the hammer 6 is inclined in the forward rotation direction as it goes forward in the rotation axis direction. That is, the angle θ _h of the striking surface 62a with respect to the front side surface 61a of the hammer body 61 of the hammer 6 (the angle formed by the front side surface 61a and the striking surface 62a) is configured to be an acute angle of less than 90 °. Here, the front side surface 61 a is a surface located on the front side in the rotation axis direction in the hammer body 61. Similarly, the hitting surface 73a on which the anvil 7 is hit while the hammer 6 is rotating forward is inclined in the forward rotation direction as it goes forward in the rotation axis direction. In other words, the angle θ _a of the hit surface 73a with respect to the front side surface 73c of the blade portion 73 of the anvil 7 (the angle formed by the front side surface 73c and the hit surface 73a) is configured to be an obtuse angle larger than 90 °. Here, the front side surface 73 c is a surface located on the front side in the rotation axis direction in the blade portion 73 of the anvil 7. The hitting surface 62a and the hitting surface 73a hit by the hitting surface 62a are inclined substantially parallel to each other as shown in FIG. Thereby, the striking force from the hammer 6 is effectively transmitted to the anvil 7.

On the other hand, the striking surface 62b that strikes the anvil 7 while the hammer 6 rotates in the reverse direction is inclined in the reverse rotation direction as it goes forward in the rotation axis direction. Similarly, the hitting surface 73b to which the anvil 7 is hit while the hammer 6 is rotating in the reverse direction is inclined in the reverse rotation direction as it goes forward in the rotation axis direction. That is, the angle θ _h is an acute angle, and the angle θ _a is an obtuse angle, like the positive rotation side striking surface 62a and the striking surface 73a. The hitting surface 62b and the hitting surface 73b hit by the hitting surface 62b are inclined substantially parallel to each other.

In the present embodiment, the inclination angles of the striking surfaces 62a and 62b and the striking surfaces 73a and 73b from the rotation axis direction are 15 ° with respect to the rotation direction, as shown in FIG. In this case, the angle θ _hIs 75 °, angle θ_aIs 105 °.

By having the inclination as described above, each claw portion 62 of the hammer 6 is formed in a substantially trapezoidal shape in which both the inner and outer side surfaces in the radial direction extend in the direction away from the hammer main body portion 61. Similarly, the radially outer surface of each blade portion 73 of the anvil 7 is formed in a substantially trapezoidal shape that extends in a direction away from the anvil body portion 71.

Next, details of the tightening operation by the impact driver 1 according to the embodiment and differences from the conventional one will be described with reference to FIGS. First, the shapes of the hammer 106 and the anvil 107 in the conventional impact driver will be described with reference to FIG. FIG. 4 is a diagram for explaining a tightening operation by a conventional impact driver, and shows the state of each part during the screw tightening operation in five stages (1) to (5). Each figure on the upper side of the drawing is a partial side view including the hammer 106 and the anvil 107, and each figure on the lower side of the drawing is a view of the hammer 106 and the anvil 107 viewed from the front side in the rotation axis direction.

In the conventional impact driver, the hammer 106 has a pair of claw portions 162 that protrude axially forward from the cylindrical hammer body portion 161. On both sides of the claw portion 162, striking surfaces 162a and 162b that are substantially parallel to the rotation axis direction of the hammer 106 are formed. The anvil 107 is disposed in front of the hammer 106 and includes a cylindrical anvil body portion 171 and a tip tool mounting portion 172. On the rear end side of the anvil body 171, a pair of blade portions 173 that protrude radially outward are provided. On both sides of the blade portion 173, hitting surfaces 173a and 173b that are substantially parallel to the rotation axis direction of the anvil 107 are formed. An opening 172a for mounting the tip tool 20 is formed at the tip of the tip tool mounting portion 172.

As described above, in the conventional impact driver, the hitting surfaces 162a and 162b of the claw portion 162 and the hitting surfaces 173a and 173b of the blade portion 173 are different from the impact driver 1 according to the present embodiment. And formed substantially parallel to the axial direction of the anvil 107. That is, the angles θ _h and θ _a are both formed at 90 °.

The tightening operation by the conventional impact driver configured as described above will be described with reference to FIGS. FIG. 6 is a diagram showing temporal changes in the tightening torque and the anvil angle during the tightening operation by the conventional impact driver and the impact driver 1 according to the embodiment. FIGS. 6A and 6B are diagrams corresponding to the conventional impact driver, and FIGS. 6C and 6D are diagrams corresponding to the impact driver 1 according to the embodiment. Here, the tightening torque means a load torque applied to the anvil 107 when the screw 30 is tightened, and the anvil angle is a rotation angle from the start of the tightening operation of the screw 30.

As shown in FIG. 4 (1), when the tip tool 20 is mounted on the tip tool mounting portion 172 and the impact driver is operated with the tip of the tip tool 20 engaged with the screw 30, the hammer 106 is As the motor and spindle (not shown) rotate, it rotates in the direction of arrow A. The hammer 106 advances in the direction of the anvil 107 as shown in FIG. 4B by urging from a spring (not shown) provided behind the hammer body 161 while continuing to rotate.

When the hammer 106 further moves forward and the claw portion 162 of the hammer 106 meshes with the blade portion 173 of the anvil 107 as shown in FIG. 4 (3), the striking surface 162a of the claw portion 162 is hit by the blade portion 173. Contact surface 173a. At this time, the striking surface 162a of the hammer 106 strikes the striking surface 173a of the blade portion 173, and the anvil 107 rotates together with the tip tool 20 in the same direction as the hammer 106. Thereby, the impact driver tightens the screw 30 with which the tip tool 20 is engaged.

At the time of this impact, a large tightening torque is momentarily applied to the anvil 107 as shown in FIG. By the application of the tightening torque, the anvil 107 and the tip tool 20 is rotated in the same direction as the hammer 106, bis 30 is to perform a rotation of a predetermined angle theta ₁ (FIG. 4 (4) and 6 (b )).

Even after a large tightening torque is momentarily generated, the hammer 106 and the anvil 107 continue to rotate while maintaining the meshing state. At this time, a striking force is applied from the striking surface 162a of the hammer 106 to the striking surface 173a of the anvil 107 in the direction perpendicular to the striking surface 162a and the striking surface 173a, that is, the rotational direction of the hammer 106 and the anvil 107. A tightening torque is applied to the. As shown in FIGS. 6A and 6B, the tightening torque gradually increases as the rotation of the screw 30 proceeds and the tightening of the screw 30 becomes deeper.

On the other hand, the striking surface 162a of the hammer 106 is struck from the striking surface 173a of the anvil 107 in the direction perpendicular to the striking surface 162a and the striking surface 173a, that is, in the direction opposite to the rotation direction of the hammer 106 and the anvil 107. A force of the same magnitude as the force will be applied. The force from the anvil 107 is denoted as F (A). The direction of the force F (A) is changed in the direction of the rotation axis by the cam mechanism (cam groove 5a, cam groove 63, steel ball 15 and the like), and the hammer 106 rotates as shown in FIG. 4 (4). An axial rearward force is applied. The force whose direction is changed by the cam is denoted as F ₁ (A). This force F ₁ (A) also increases gradually as the rotation of the screw 30 proceeds, similarly to the tightening torque.

Also, the urging force of the spring is applied to the hammer 106 in a direction toward the anvil 107, that is, in the forward direction of the rotation axis. The urging force by the spring is denoted as F (S). This urging force F (S) gradually decreases as the hammer body 161 moves toward the anvil 107, that is, as the screw 30 rotates.

In the state shown in FIG. 4 (4), a force F in the rearward direction of the rotation axis based on the tightening torque.₁(A) is smaller than the forward force F (S) in the rotational axis direction by the spring, so that the hammer 106 is urged toward the anvil 107, and the claw portion 162 and the blade portion 173 maintain the meshing state and rotate. continue. As the rotation of the screw 30 proceeds, the force F based on the tightening torque₁(A) increases, and the force F (S) by the spring decreases. And force F₁After the magnitude of (A) becomes equal to the magnitude of the force F (S) (FIG. 4 (5)), when the screw 30 further rotates, the force F ₁The magnitude of (A) becomes larger than the magnitude of the force F (S), and a force acting backward in the direction of the rotation axis acts on the hammer 106. Thereby, the claw portion 162 of the hammer 106 gets over the blade portion 173 of the anvil 107, and the engagement between the hammer 106 and the anvil 107 is released.

When the engagement between the hammer 106 and the anvil 107 is released, as shown in FIG. 6A, the tightening torque of the anvil 107 becomes 0, and the rotation of the anvil 107, the tip tool 20, and the screw 30 is stopped. The screw 30 stops rotating after rotating by a predetermined angle θ ₁ and further rotating by an angle θ ₂ . That is, the rotation angle of the screw 30 in one hit, that is, the anvil angle is θ ₃ = θ ₁ + θ ₂ .

Also, assuming that the impact time of one impact is T, the time from (3) to (5), that is, the time t ₁ during which torque is generated, and the states from (5) to (1), (2) The time until the state (3) is reached again, that is, the sum of the time t _{2 when} no torque is generated, can be expressed as T = t ₁ + t ₂ . Hereinafter, the time t ₁ when the torque is generated is defined as the valid time, and the time t ₂ when the torque is not generated is defined as the invalid time.

After the hammer 106 and the anvil 107 are disengaged from each other, the hammer 106 moves backward, but moves forward again by the bias of the spring and strikes the anvil 107. Then, a tightening torque is applied to the anvil 107, and the tip tool 20 tightens the screw 30.

Subsequently, a tightening operation by the impact driver 1 according to the present embodiment will be described with reference to FIGS. 5 and 6.

As shown in FIG. 5 (1), when the impact driver 1 is operated with the tip tool 20 mounted on the tip tool mounting portion 72 and the tip of the tip tool 20 engaged with the screw 30, the hammer 6 is As the motor 3 and the spindle 5 rotate, it rotates in the direction of arrow A. The hammer 6 advances in the direction of the anvil 7 as shown in FIG. 5B by urging from the spring 16 while continuing to rotate. When the claw portion 62 of the hammer 6 is engaged with the blade portion 73 of the anvil 7 as shown in FIG. 5 (3), the striking surface 62 a of the claw portion 62 contacts the hit surface 73 a of the blade portion 73. At this time, the striking surface 62 a of the hammer 6 strikes the striking surface 73 a of the blade portion 73, and the anvil 7 rotates in the same direction as the hammer 6 together with the tip tool 20. Thereby, the impact driver 1 clamp | tightens the screw | thread 30 with which the front-end tool 20 engages similarly to the past.

At the time of this impact, as shown in FIG. 6C, a large tightening torque is instantaneously applied to the anvil 7 as in the conventional case. By applying the tightening torque, the anvil 7 and the tip tool 20 rotate in the same direction as the hammer 6 and the screw 30 rotates by a predetermined angle θ ₁ (FIGS. 5 (4) and 6 (d). )).

Even after a large tightening torque is momentarily generated, the hammer 6 and the anvil 7 continue to rotate while maintaining the meshing state. At this time, a striking force is applied in a direction perpendicular to the striking surface 62a and the striking surface 73a from the striking surface 62a of the hammer 6 to the striking surface 73a of the anvil 7, and the anvil 7 has a tightening torque in the rotational direction. Will be granted. As shown in FIGS. 6C and 6D, the tightening torque gradually increases as the screw 30 rotates.

On the other hand, on the striking surface 62a of the hammer 6, a force F (A) having the same magnitude as the above-mentioned striking force is exerted from the striking surface 73a of the anvil 7 in a direction perpendicular to the striking surface 62a and the striking surface 73a. Will join. Here, in the impact driver 1 of the present embodiment, unlike the conventional impact driver, the striking surface 62a and the striking surface 73a are not parallel to the rotation axis direction but have an inclination, so that the hammer 6 strikes the anvil 7. The direction of the force is not the same as the rotational direction, and the direction of the force F (A) from the anvil 7 to the hammer 6 is not opposite to the rotational direction, as shown in FIG. 5 (4). Therefore, the force F (A) has not only a force component in the rotation direction but also a force component in the rotation axis direction.

Among these components, the force component in the rotational direction is converted in the direction of the rotational axis by the cam as in the case of the conventional impact driver, and becomes a force in the axially rearward direction. This axially rearward force is denoted as F ₁ (A) (FIG. 5 (4)). The force component in the rotation axis direction is a force forward in the axial direction. This axially forward force is denoted as F ₂ (A) (FIG. 5 (4)). That is, a force in the same direction as the biasing force F (S) from the spring 16 is applied to the hammer 6, and the force F ₂ (A) is a force that assists the biasing force F (S) from the spring 16.

Force F based on tightening torque₁(A) and F₂(A) gradually increases as the rotation of the screw 30 proceeds. In contrast, the force F (S) from the spring 16 gradually decreases as the rotation of the screw 30 proceeds. In the state shown in FIG. 5 (4), the force F to the rear in the rotational axis direction based on the tightening torque.₁(A) is a force F (S) forward in the rotational axis direction by the spring 16 and a force F forward in the rotational axis direction based on the tightening torque.₂Sum of (A) F (S) + F₂Since it is smaller than (A), the hammer 6 is urged in the direction of the anvil 7, and the claw portion 62 and the blade portion 73 continue to rotate while maintaining the meshing state. The force F based on the tightening torque as the screw 30 advances. ₁The magnitude of (A) is the force F (S) by the spring 16 and the force F based on the tightening torque.₂Sum of (A) F (S) + F₂After becoming equal to (A) (FIG. 5 (5)), the force F₁(A) is force F (S) + F₂If it becomes larger than (A), a force in the rearward direction of the rotation axis acts on the hammer 6. Thereby, as shown in FIG. 5 (5), the claw portion 62 of the hammer 6 gets over the blade portion 73 of the anvil 7, and the engagement between the hammer 6 and the anvil 7 is released.

In the impact driver 1 according to the present embodiment, the force F ₂ (A) forward in the rotational axis direction based on the tightening torque becomes a force that assists the biasing force F (S) from the spring 16, so that the spring 16 Will act as if the spring constant of is increased. Thereby, the detachment torque of the hammer 6 and the anvil 7 becomes larger than that of the conventional impact driver. Accordingly, in one stroke, the time until the hammer 6 and the anvil 7 are disengaged, that is, the time from (3) to (5) becomes longer.

When the hammer 6 and the anvil 7 are disengaged, as shown in FIG. 6C, the tightening torque of the anvil 7 becomes zero, and the rotation of the anvil 7, the tip tool 20, and the screw 30 stops. The screw 30 stops rotating after rotating by a predetermined angle θ ₁ and further rotating by an angle θ ₂ ′. That is, the rotation angle of the screw 30 in this one hit, that is, the anvil angle is θ ₃ ′ = θ ₁ + θ ₂ ′. Here, since θ ₂ ′> θ ₂ , θ ₃ ′> θ ₃ .

The striking time T for one striking is approximately the same length as that of a conventional impact driver. However, (3) from up to (5) times, i.e. effective time t ₁ which torque is generated _'is longer than the effective time t ₁ in the conventional impact driver. This is because the force F (A) based on the tightening torque has a component F ₂ (A) forward in the axial direction, and assists the force F (S) of the spring 16. Therefore, the transmission amount of torque from the hammer 6 to the anvil 7 increases due to the difference in effective time t ₁ ′ −t ₁ , and the anvil angle in one hit also increases by Δθ ₂ = θ ₂ ′ −θ ₂ .

After the engagement between the hammer 6 and the anvil 7 is released, the hammer 6 moves backward, but moves forward again by the bias of the spring 16 and strikes the anvil 7. Then, a tightening torque is applied to the anvil 7, and the tip tool 20 tightens the screw 30.

As described above, in the impact driver 1 of the present embodiment, the anvil angle in one hit is larger than that of a conventional impact driver. This is because the striking surface 62a and the striking surface 73a are inclined (the angle θ _h is an acute angle, the angle θ _a is an obtuse angle, and the hammer 6 and the anvil 7 are inclined to approach each other). This is because a force assisting the force is generated, and the effective time during which the torque is transmitted is increased.

In the above description, the description has been given by taking the impact while the motor 3 is rotating forward as an example, but the same applies to the impact when the motor 3 is rotating in the reverse direction. During the forward rotation of the motor 3, the hammer 6 and the anvil 7 rotate counterclockwise when viewed from the front, and the striking surface 62 a of one claw portion 62 of the hammer 6 strikes the hit surface 73 a of one blade portion 73 of the anvil 7. Then, the striking surface 62 a of the other claw portion 62 strikes the striking surface 73 a of the other blade portion 73. On the other hand, during reverse rotation of the motor 3, the hammer 6 and the anvil 7 rotate clockwise when viewed from the front, and the striking surface 62 b of the one claw portion 62 of the hammer 6 is hit by the other blade portion 73 of the anvil 7. The surface 73 b is hit, and the hit surface 62 b of the other claw portion 62 hits the hit surface 73 b of the one blade portion 73. The force component forward of the striking force in the direction of the rotation axis assists the urging force of the spring 16, and the hammer 6 and the anvil 7 are not easily disengaged. Therefore, the effective time during which torque is transmitted is lengthened, and the anvil angle in one hit is increased.

Next, the case where the screw 30 having a length of 75 mm is tightened will be described with reference to FIGS. FIG. 7 is a diagram showing the time change of the anvil angle during the tightening operation by the conventional impact driver, and FIG. 8 shows the time change of the anvil angle during the tightening operation by the impact driver 1 according to the embodiment. FIG.

In order to complete the tightening operation of the 75 mm screw 30, it is necessary to rotate the screw 30 times. In other words, it is necessary to hit until the anvil angle reaches 10800 °. When the tightening operation was performed with a conventional impact driver, the anvil angle reached 10800 ° after 150 hits. The time required for this tightening operation is about 3 seconds. On the other hand, when the tightening operation was performed by the impact driver 1 according to the embodiment, the anvil angle reached 10800 ° by 120 hits. The time required for this tightening operation is about 2.5 seconds. That is, the conventional impact driver requires 1.2 times as long as one screw.

FIG. 9 is a diagram for explaining the details of the tightening operation by the conventional impact driver and the impact driver 1 according to the embodiment. FIG. 9 shows a conventional impact driver (conventional product) and impact driver 1 according to the embodiment (inventive product), impact time per impact (T), number of impacts per second, and completion of tightening. The total number of hits, the tightening time per screw, and the screw rotation angle (anvil angle) per hit are shown.

For both the conventional impact driver and the impact driver 1 according to the embodiment, the hitting time T per hit is 0.02 seconds, and the hit count per second is 50 times. However, the total number of hits until the tightening is completed is 150 times with the impact driver according to the embodiment, while it is 150 times with the conventional impact driver. Further, as described above, the tightening time per screw is 3 seconds with the conventional impact driver, but is shortened to 2.5 seconds with the impact driver 1 according to the embodiment. From this, the screw rotation angle per hit is θ ₃ = 72 ° in the conventional impact driver, whereas it is as large as θ ₃ ′ = 86.4 ° in the impact driver 1 according to the embodiment. I understand that.

As described above, according to the impact driver 1 according to the present embodiment, the hammering surfaces 62 a and 62 b of the claw 62 of the hammer 6 and the hit surfaces 73 a and 73 b of the blade 73 of the anvil 7 are the hammer 6. And the anvil 7 are formed so as to be inclined with respect to the rotation axis direction, so that the detachment torque of the hammer 6 and the anvil 7 is compared with the case where the striking surface and the hit surface are formed parallel to the rotation axis direction. Becomes larger. Accordingly, the same effect as that obtained when the spring constant of the spring 16 is increased is obtained, and the speed of the tightening operation is improved.

While the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the impact driver has been described as an example of the above-described impact tool, but the present invention can also be applied to other impact tools such as an impact wrench.

DESCRIPTION OF SYMBOLS 1 ... Impact driver, 3 ... Motor, 5 ... Spindle, 6 ... Hammer, 7 ... Anvil, 61 ... Hammer main body part, 61a ... Front side surface, 62 ... Claw part, 62a, 62b ... Strike surface, 71 ... Anvil main body part, 72 ... Tip tool mounting portion, 73 ... Blade portion, 73a, 73b ... Impact surface, 73c ... Front side surface

Claims (5)

A motor,
A hammer driven to rotate by the motor;
A striking tool having a mounting portion to which a tip tool is mounted, and an anvil that rotates in the rotation direction of the hammer by striking from the hammer,
The hammer has a striking surface that inclines in the rotation direction toward the tip tool side on the side in contact with the anvil in the rotation direction,
The striking tool, wherein the anvil has a striking surface that inclines in the rotation direction toward the tip tool side on the side in contact with the hammer in the rotation direction. The hammer protrudes from the hammer body portion to the tip tool side, and has a claw portion having the striking surface,
The impact tool according to claim 1, wherein the anvil has a blade portion protruding in a radial direction from the anvil body portion and having the hit surface. The striking tool according to claim 1, wherein the striking surface and the striking surface are inclined substantially parallel to each other. A motor,
A hammer body portion, and a claw portion protruding forward from the hammer body portion and having a striking surface, and a hammer driven to rotate by the motor;
A blade portion provided on the front side of the hammer, provided on the front side and provided with a tip tool, and a blade portion provided on the rear side and projecting in a radial direction from the anvil main body and contacting the striking surface. And an anvil that rotates in the direction of rotation of the hammer by striking from the hammer,
The angle formed between the front side surface of the hammer main body and the striking surface is less than 90 °, and the angle formed between the front side surface of the anvil main body and the hit surface is configured to be greater than 90 °. A striking tool characterized by The striking tool according to claim 4, wherein the striking surface and the striking surface are inclined substantially parallel to each other.

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