JP2021074796A - Striking tool - Google Patents

Abstract

To effectively reduce weight while ensuring a reciprocating guide function.SOLUTION: A hammer drill 1 includes a motor 6, a tool holder 17 capable of installing a bit B at a front end, and a striker 24 provided in the tool holder 17 and reciprocated by the driving of the motor 6, and can strike the bit B with the reciprocating of the striker 24. The striker 24 is equipped with a large-diameter portion 30 on a rear side, and a small-diameter portion 31 on a front side. The large-diameter portion 30 is formed with two holes 34 and 34 opening on an outer peripheral surface.SELECTED DRAWING: Figure 1

Description

The present invention relates to a striking tool such as a hammer drill that reciprocates a striker to strik a bit at the tip.

A striking tool such as a hammer drill is equipped with a tool holder that can attach a bit to the tip, and in the tool holder, a piston (including a piston cylinder) that reciprocates by driving a motor and an air spring work in conjunction with the piston. It houses a reciprocating striker (also called a "striker"). The striker hits the bit directly or indirectly through an impact bolt (also called a "meson").
In such a striking tool, the weight of the striker may be reduced in consideration of the mass required for striking and the burden on the operator. For example, in Patent Document 1, in order to achieve high output and weight reduction, a hole is formed in a floating piston (striker) so as to be orthogonal to the striking axis and have a diameter of 1/2 to 3/4 of the outer diameter. The invention is disclosed.

Japanese Patent No. 5584408

However, since the invention of Patent Document 1 is a technique for forming one hole in the striker, if the hole is made too large, the outer peripheral surface of the striker, which serves as a guide for reciprocating movement, is largely scraped at one place to provide a guide function. It may decrease. However, if the holes are made smaller, it will not be possible to achieve sufficient weight reduction.

Therefore, an object of the present invention is to provide a striking tool capable of achieving effective weight reduction while ensuring a reciprocating guide function.

In order to achieve the above object, the invention according to claim 1 includes a motor and a motor.
A tool holder that can attach a bit to the front end,
Includes a striker that is installed in the tool holder and reciprocates when driven by a motor.
It is a striking tool that can hit a bit as the striker reciprocates.
The striker is characterized in that a plurality of holes that open on the outer peripheral surface are formed.
The invention according to claim 2 is characterized in that, in the above configuration, the diameter of each hole is less than 1/2 of the outer diameter of the striker.
The invention according to claim 3 is characterized in that, in the above configuration, the plurality of holes are formed in different directions from each other.
The invention according to claim 4 is characterized in that, in the above configuration, the plurality of holes communicate with each other.
The invention according to claim 5 is characterized in that, in the above configuration, a plurality of holes are formed in parallel with each other.
The invention according to claim 6 is characterized in that, in the above configuration, the diameters of the holes are all the same.
In the invention according to claim 7, in the above configuration, the striking point of the bit on the front surface of the striker is eccentric from the axis of the striker, and an opening of a hole is formed on the outer peripheral surface of the striker in the axial direction on the eccentric side. It is characterized by not being located.
The invention according to claim 8 is characterized in that, in the above configuration, a ventilation groove extending in the axial direction of the striker is formed at a position other than the opening of the hole on the outer peripheral surface of the striker.
The invention according to claim 9 is characterized in that, in the above configuration, each hole is formed through a striker.
The invention according to claim 10 is characterized in that, in the above configuration, the striker has a small diameter portion on the front side and a large diameter portion on the rear side, and each hole is formed in the large diameter portion. ..
The invention according to claim 11 is characterized in that, in the above configuration, the striker is held in a tool holder and housed in a piston cylinder that reciprocates by driving a motor.
The invention according to claim 12 has, in the above configuration, an intermediate shaft that is supported in parallel with the tool holder and rotates by driving a motor, and a conversion mechanism that converts the rotation of the intermediate shaft into a reciprocating motion of the arm. The piston cylinder is characterized in that it is connected to an arm.

According to the present invention, since a plurality of holes are formed in the striker, the size of each hole can be suppressed, and the outer peripheral surface of the striker is not largely scraped at one place. Therefore, effective weight reduction can be achieved while ensuring the guide function of the reciprocating movement by the outer peripheral surface.
In particular, if the diameter of each hole is less than 1/2 of the outer diameter of the striker, the guide function can be secured and the weight can be reduced in a well-balanced manner.
Further, if the holes are formed in different directions, the outer peripheral surface serving as the guide surface can be left evenly even if a plurality of holes are provided, and a good guide function can be maintained.
Further, if a plurality of holes are communicated with each other, the holes can be brought close to each other in the axial direction to secure a long outer peripheral surface before and after the striker.
Further, if the diameters of the holes are all the same, the processing can be easily performed.
If the striking point of the bit on the front surface of the striker is eccentric from the axis of the striker, the striking point can be eccentric if the opening of the hole is not positioned on the outer peripheral surface of the striker in the axial direction on the eccentric side. However, durability on the eccentric side can be ensured.
Further, if a ventilation groove extending in the axial direction of the striker is formed at a place other than the opening of the hole on the outer peripheral surface of the striker, even if the hole is provided, the ventilation action accompanying the reciprocating movement of the striker is not affected.

It is a central vertical sectional view of a hammer drill. In the explanatory view of the striker, (A) is a perspective view, (B) is a side view, and (C) is a sectional view taken along line AA. An explanatory view of a modified example of the striker, (A) is a perspective view, (B) is a side view, and (C) is a sectional view taken along line BB. An explanatory view of a modified example of the striker, (A) is a perspective view, (B) is a front view, and (C) is a sectional view taken along line CC.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a central vertical cross section showing an example of a hammer drill.
The hammer drill 1 has a housing 2 extending in the front-rear direction. The housing 2 includes a front housing 3, a rear housing 4 assembled on the rear side of the front housing 3, and a handle housing 5 assembled on the rear side of the rear housing 4. Inside the rear housing 4, the motor 6 is housed in a posture in which the output shaft 7 is directed forward. A switch 8 in which the trigger 9 is projected forward is housed in the handle housing 5, and a power cord (not shown) is connected to the handle housing 5.
The inner housing 10 is held in the front housing 3. The front end of the output shaft 7 of the motor 6 penetrates the inner housing 10 and is supported by the inner housing 10. The front end of the output shaft 7 projects into the front housing 3 and is provided with a pinion 11.

In the front housing 3, the intermediate shaft 12 is rotatably supported with its axis oriented in the front-rear direction. A gear 13 is provided at the rear end of the intermediate shaft 12 and meshes with the pinion 11 of the output shaft 7. The intermediate shaft 12 is provided with a first gear 14, two clutches 15, 15 and a boss sleeve 16 from the front. The first gear 14 and the boss sleeve 16 can rotate with respect to the intermediate shaft 12, and the clutches 15 and 15 can rotate integrally with the intermediate shaft 12 by spline coupling.
Above the intermediate shaft 12, a tubular tool holder 17 is rotatably supported with its axis oriented in the front-rear direction. The front end of the tool holder 17 projects forward from the front housing 3. An operation sleeve 18 for attaching / detaching the bit B is provided at the front end of the tool holder 17. A piston cylinder 19 is inserted into the rear end of the tool holder 17 so as to be movable back and forth from the rear.

The ring 20 is externally attached to the boss sleeve 16 via a bearing 21 whose axis is tilted with respect to the intermediate shaft 12. The ring 20 is provided with an arm 22 that projects upward, and the upper end of the arm 22 is connected to the rear end of the piston cylinder 19. The ring 20 and the bearing 21 form a conversion mechanism that converts the rotation of the intermediate shaft 12 into the reciprocating motion of the arm 22.
Inside the piston cylinder 19, the striker 24 is housed so as to be movable back and forth via the air chamber 23. An impact bolt 25 is housed in the tool holder 17 in front of the striker 24 so as to be movable back and forth. The tool holder 17 is provided with a second gear 26 and meshes with the first gear 14.

The striker 24 is a metal member having a large diameter portion 30 on the rear side and a small diameter portion 31 on the front side. A ring groove 32 is formed at the rear portion of the large diameter portion 30. The ring groove 32 is covered with an O-ring 33 that is in sliding contact with the piston cylinder 19.
As shown in FIG. 2, two holes 34, 34 are formed in the large diameter portion 30 on the front side of the ring groove 32. The holes 34 and 34 penetrate the large diameter portion 30 so that the axis lines 34a intersect the axis lines 24a of the striker 24 at right angles to each other. Both ends of each hole 34 are circularly opened on the outer peripheral surface of the large diameter portion 30. The diameter D1 of each hole 34 is less than 1/2 of the outer diameter D of the large diameter portion 30.
The holes 34, 34 are formed in different directions so that the axes 34a intersect each other at right angles in a front view. The holes 34, 34 communicate with each other inside the large diameter portion 30.

A ventilation groove 35 extending in the axis 24a direction is formed between the openings of the holes 34 and 34 on the outer peripheral surface of the large diameter portion 30. The ventilation groove 35 communicates the air chamber 23 on the rear side of the large diameter portion 30 with the front side of the large diameter portion 30 in the piston cylinder 19. The ventilation groove 35 adjusts the pressure of the air chamber 23 when the striker 24 reciprocates.
The small diameter portion 31 is formed coaxially with the large diameter portion 30. The front surface of the small diameter portion 31 is a convex curved surface 36 that bulges forward. However, the striking point P, which is the maximum height of the convex curved surface 36 in the forward direction, is not on the axis 24a of the striker 24, but is eccentric to the outside in the radial direction of the convex curved surface 36. The openings of the holes 34 and 34 are not located on the outer peripheral surface 30a (upper side of FIGS. 2B and 2C) of the large diameter portion 30 located on the eccentric side. Therefore, the outer peripheral surface 30a on the eccentric side of the striking point P is continuous in the axial direction 24a.

A switching knob 40 is provided on the lower surface of the front housing 3. The switching knob 40 moves the clutches 15 and 15 back and forth by a rotation operation. By operating the switching knob 40, the clutches 15 and 15 are in the first switching position where only the front clutch 15 engages with the first gear 14, and the second switching position where only the rear clutch 15 engages with the boss sleeve 16. , The front and rear clutches 15 and 15 move to any of the third switching positions where the first gear 14 and the boss sleeve 16 are engaged with each other.
At the first switching position of the clutches 15 and 15, the tool holder 17 rotates via the second gear 26 to rotate the bit B in the drill mode. At the second switching position of the clutches 15 and 15, the rotation of the boss sleeve 16 is converted into the reciprocating movement of the arm 22. Therefore, the piston cylinder 19 reciprocates, and the striker 24 interlocks and reciprocates via the air chamber 23. Therefore, the hammer mode is set in which the bit B is hit through the impact bolt 25. At the third switching position of the clutches 15 and 15, the hammer drill mode is set in which the tool holder 17 is rotated and the impact bolt 25 is hit at the same time.

In the hammer drill 1 configured as described above, when the trigger 9 is pushed in by the hand holding the handle housing 5 to turn on the switch 8, the motor 6 is driven and the output shaft 7 is rotated. Then, the intermediate shaft 12 rotates, and the bit B is rotated and / or hit in the operation mode selected by the switching knob 40. A side handle 41 is provided at the front end of the front housing 3, and the hammer drill 1 can be supported on the front side of the housing 2.
Since the striker 24 that reciprocates in the hammer mode and the hammer drill mode is lightened by the holes 34 and 34, the overall weight of the hammer drill 1 is also smaller than before, and the burden on the operator is reduced. To. Further, since the diameter D1 of the hole 34 is suppressed to be smaller than 1/2 of the diameter D of the large diameter portion 30, the reciprocating movement is guided by the outer peripheral surface of the large diameter portion 30 without any trouble.

If the striker 24 advances while the bit B is not attached or the bit B is not pressed against the work piece, it collides with the impact bolt 25 at the non-impact position. However, since the striking point P is eccentric, the striker 24 is tilted by applying a radial force, so that the striker 24 is suppressed from bouncing after the collision. Therefore, the striker 24 is held by the holder 27 as it is, and subsequent blank shots are prevented.

As described above, the hammer drill 1 of the above-described embodiment includes the motor 6, the tool holder 17 to which the bit B can be mounted at the front end, and the striker 24 provided in the tool holder 17 and reciprocating by driving the motor 6. The striker 24 is formed with a plurality of holes 34, 34 that open on the outer peripheral surface.
With this configuration, the size of each hole 34 can be suppressed, and the outer peripheral surface of the striker 24 is not largely scraped at one place. Therefore, effective weight reduction can be achieved while ensuring the guide function of the reciprocating movement by the outer peripheral surface.

In particular, the diameter D1 of each hole 34 is less than 1/2 of the outer diameter D of the striker. Therefore, it is possible to achieve a good balance between ensuring the guide function and reducing the weight.
Further, the holes 34 and 34 are formed in different directions from each other. Therefore, even if the holes 34 and 34 are provided, the outer peripheral surface serving as the guide surface can be left evenly, and a good guide function can be maintained.
Further, the holes 34 and 34 communicate with each other. Therefore, the holes 34, 34 can be brought close to each other in the direction of the axis 24a to secure a long outer peripheral surface before and after the large diameter portion 30.
Moreover, the diameter of each hole 34 is the same. Therefore, processing can be easily performed.

Further, the striking point P of the bit B on the front surface of the striker 24 is eccentric from the axis 24a of the striker 24, and holes 34 and 34 are opened on the outer peripheral surface 30a of the striker 24 in the axis 24a direction on the eccentric side. Not located. Therefore, even if the striking point P is eccentric, durability on the eccentric side can be ensured.
Further, a ventilation groove 35 extending in the direction of the axis 24a of the striker 24 is formed at a position other than the openings of the holes 34 and 34 on the outer peripheral surface of the striker 24. Therefore, even if the hole 34 is provided, it does not affect the ventilation action associated with the reciprocating movement of the striker 24.

The striker holes do not have to communicate with each other as in the above embodiment. That is, as shown in FIG. 3, the holes 34, 34 can be formed so as to be separated from each other in the front-rear direction in the axial direction 24a so as not to communicate with each other.
Further, the different directions of the holes are not limited to orthogonal shapes, and may intersect at different angles.
Further, the holes are not limited to the case where they are formed in different directions. That is, as shown in FIG. 4, the holes 34 and 34 may be formed in parallel with each other. In this case, since it is not necessary to change the orientation when the striker 24 is manufactured, the hole 34 can be easily machined.
In the striker 24 of FIGS. 3 and 4, a convex curved surface is not formed on the front surface of the small diameter portion 31. Therefore, the front surface of the small diameter portion 31 comes into contact with the impact bolt 25.

Further, the diameters of the holes are not all the same, and some or all of them may have different diameters. The number of holes is not limited to two, and three or more holes may be formed.
Further, the hole may be a bottomed hole that does not penetrate all or part of the hole. The shape of the hole is not limited to a circle.
Further, the striker is not limited to a two-stage shape having a large diameter portion and a small diameter portion, and may have a structure in which the striking point is not eccentric even if there is a convex curved surface.
Further, there may be a plurality of ventilation grooves, or the ventilation grooves may be located at positions passing through the openings of the holes.

In addition, the shape and type of the motor can be changed as appropriate for the form of the hammer drill. Instead of a power cord, it may be a DC machine equipped with a battery pack as a power source.
In addition, it is not limited to the structure that reciprocates the piston cylinder with the intermediate shaft and the conversion mechanism, but it is a hammer drill that adopts a crank mechanism and reciprocates the piston in the cylinder held in the tool holder to interlock the striker. May be good. The operation modes that can be selected are not limited to three, and a structure in which the striker directly hits the bit without an impact bolt is also included.
Furthermore, the present invention is applicable not only to hammer drills but also to other striking tools such as electric hammers.

1 ... Hammer drill, 2 ... Housing, 6 ... Motor, 7 ... Output shaft, 12 ... Intermediate shaft, 17 ... Tool holder, 19 ... Piston cylinder, 22 ... Arm, 23 ... Air chamber, 24 ... striker, 24a ... axis, 25 ... impact bolt, 30 ... large diameter, 30a ... outer circumference, 31 ... small diameter, 34 ... hole, 34a ... axis, 35 ... ventilation groove , D ... Large diameter outer diameter, D1 ... Hole diameter, P ... Impact point.

Claims (12)

With the motor
A tool holder that can attach a bit to the front end,
Includes a striker provided in the tool holder and reciprocating driven by the motor.
A striking tool capable of striking the bit as the striker reciprocates.
A striking tool characterized in that the striker is formed with a plurality of holes that open on the outer peripheral surface. The striking tool according to claim 1, wherein the diameter of each of the holes is less than 1/2 of the outer diameter of the striker. The striking tool according to claim 1 or 2, wherein the plurality of holes are formed in different directions from each other. The striking tool according to any one of claims 1 to 3, wherein the plurality of holes communicate with each other. The striking tool according to claim 1 or 2, wherein the plurality of holes are formed in parallel with each other. The striking tool according to any one of claims 1 to 5, wherein the diameters of the holes are all the same. The hit point of the bit on the front surface of the striker is eccentric from the axis of the striker, and the opening of the hole is not located on the outer peripheral surface of the striker in the axial direction on the eccentric side. The striking tool according to any one of claims 1 to 6. The striking tool according to any one of claims 1 to 7, wherein a ventilation groove extending in the axial direction of the striker is formed at a position other than the opening of the hole on the outer peripheral surface of the striker. The striking tool according to any one of claims 1 to 8, wherein each hole is formed through the striker. The striker has a small diameter portion on the front side and a large diameter portion on the rear side, and each of the holes is formed in the large diameter portion, according to any one of claims 1 to 9. Strike tool. The striking tool according to any one of claims 1 to 10, wherein the striker is held in the tool holder and housed in a piston cylinder that reciprocates by driving the motor. It has an intermediate shaft that is supported in parallel with the tool holder and rotates by driving the motor, and a conversion mechanism that converts the rotation of the intermediate shaft into a reciprocating motion of the arm, and the piston cylinder is connected to the arm. The striking tool according to claim 11, wherein the striking tool is provided.

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