JPS5834270B2 - electric hammer drill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a rotary striking and rotationally driven electric hammer drill equipped with a striking element driven by an air spring.

Generally, rotary impact in an electric hammer drill is performed by compressing air between the impactor and the piston, and rotation is performed by a gear and key connection.

Moreover, the striking stop is performed by moving the position of the tool holder to disable compression of air between the striking element and the piston.

In this conventional impact stopping means, the tool holder is attached to a sleeve-like member that is displaceable in the axial direction of the cylinder with respect to the housing, and the tool holder is displaceable between an impact operation position and an impact non-operation position. There is a method in which the sleeve is fixed at each position, or a method in which the striker is provided and operated separately from a fixing device for inhibiting the grasping movement.

However, these devices have drawbacks such as a complicated structure and a large main body.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electric hammer drill that eliminates the above-mentioned drawbacks, has a simple structure, is compact, and has improved operability.

The electric hammer drill of the present invention includes a cylinder that is rotatably driven in a cylinder case via a drive source, houses a striking element therein, and forms an air chamber, and is slidably attached to the cylinder and is driven by the drive source. A piston and a tip tool member are removably attached and driven to rotate integrally with the cylinder, and are slidable a predetermined distance in the axial direction, are pressed and attached via a spring so as to be displaced toward the tip side, and are driven reciprocally through the piston. a tool holder, and a ventilation hole for the air chamber formed at a position that communicates with the air chamber during stoppage and is blocked via the striker when the tool holder is retracted, and the air chamber is provided with a vent hole that communicates with the air chamber when the tool holder is stopped, and is closed through the striker when the tool holder is retracted; and a length of a shank portion that is attached to the tool holder and contacts the intermediate member so that the ventilation hole of the air chamber is not blocked through the striker when the tool holder is retracted. A tip tool member whose length is shortened and a tip tool member whose length is not shortened are provided.

That is, when the tool holder moves toward the drill in the axial direction, the air between the striking element and the piston enters and exits through the ventilation hole of the cylinder, stopping the striking operation, and the tip tool member during rotational striking and the tip tool member during rotation only. Focusing on the fact that the tip tool member is different, in the case of a rotary-only tip tool member, the axial length of the attachment part is shortened so that the intermediate in the tool holder can move to the above-mentioned non-impacting position. It is movable to the operating position.

Note that rotary impact is mainly used for drilling holes in concrete, tiles, etc., and has an obtuse tip, whereas rotary impact is used for drilling wood and steel plates, and the tip has an acute angle, and both can be done with the same tip tool. There isn't.

An embodiment of the electric hammer drill of the present invention will be described below with reference to FIG.

1 is a first gear driven by a motor rotor (not shown) of the drive source, and meshes with a second gear 2 that performs deceleration; 3 is a crankshaft integrally fixed to the second gear 2; An eccentric pin 4 is fixed in position, and one end of a connecting rod 5 is rotatably attached to the eccentric pin 4.

A cylinder 6 is rotatably supported within a cylinder case 7 via ball bearings 8 and 9.

Reference numeral 10 denotes a tool holder, which is movable in the axial direction by a ball 26 fitted in a hole 28 of the cylinder 6 and a long groove 11 formed in the tool holder 10, and is rotated integrally with the cylinder 6. It has become.

Reference numeral 12 denotes an intermediate member which is engaged by a ball 14 fitted into a hole 29 of the tool holder 10 and a groove 13 formed in the intermediate member 12, and is formed so as to be movable over the distance of the groove 13.
It is arranged between the striking element 17 and the shank portion 27 of the tip tool member 15 for rotary striking.

Although the tip tool member 15 is a drill in the illustrated case, it may be an auxiliary tool such as a drill chuck holder, and the tip tool member 15 is attached to the tool holder 10 via a roller 16.

17 is a striking element slidably fitted into the cylinder 6;
A piston 8 is slidably fitted into the cylinder 6 and is connected to the other end of the connecting rod 5 via a piston pin 19.

Reference numerals 20 and 21 are vent holes provided in the cylinder 6, and 22 is an air chamber constituted by the cylinder 6, the striker 17, and the piston 18.

A third gear 23 is fixed coaxially with the bevel gear 24 and meshes with the second gear 2.

The bevel gear 24 meshes with a bevel gear 25 fixed to the outer periphery of the cylinder 2.

FIG. 1 shows the rotary impact movement, in which the tip tool member 15 is in contact with the workpiece (not shown), and therefore the spring 30 is in contact with the workpiece (not shown).
is compressed and the meson 12 is pushed up, so the air chamber 2
The air in the air chamber 22 compressed by the movement of the piston 18 imparts linear kinetic energy to the striker 17 and strikes the tip tool member 15 via the intermediate member 12 .

Further, the cylinder 6 is rotationally driven via the second gear 2, the third gear 23, and the bevel gears 24 and 25, and the rotation of the cylinder 6 is transmitted to the tip tool member 15 via the tool holder 10.

When the tip tool member 15 is released from the workpiece, the tension of the spring 30 pushes the tool holder 15 forward by the length of the long groove 11 as shown in FIG. In order to pass and move forward, the air chamber 22 is opened and the movement of the striking element 17 is stopped.

FIG. 3 shows a state in which a rotation-only tip tool member 15A is attached.

The shank portion 27 of the tip tool member 15A is connected to the groove 13 of the intermediate member 12 from the shank 27 of the tip tool member 15 for rotary impact.
The comb is short by the amount of play in the axial direction formed by the ball 14 and the ball 14.

Therefore, when the tip tool member 15A is in contact with the workpiece, the pressing force is received by the ball 26 via the roller 16.

Since the intermediate element 12 moves forward by the amount of play in the groove 13, the striker 17 passes through the ventilation hole 20 of the cylinder 6 and moves forward, so that the air chamber 2
2 is opened and the movement of the striking element 1γ is stopped.

On the other hand, the rotation is transmitted to the tip tool member 15A via the tool holder 10 and the roller 16.

As described above, in the electric hammer drill of this embodiment, the axial length of the attachment part of the tip tool member exclusively for rotation is formed to be short so that the intermediate in the tool holder can be moved to the striking non-operating position. .

That is, by using the components necessary for rotary impact and adjusting the amount of movement of the meson by shortening the length of the shank portion of the tip tool member, it is possible to change the rotational impact in one rotation.

The simple structure makes it possible to reduce the size and weight, and in the case of switching between rotary blows and one rotation, the tip tool must also be replaced, so both operations can be performed at the same time, and the operation is easy.

As described above, the electric hammer drill of the present invention has advantages such as a simple structure, small size and light weight, and improved operability.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the electric hammer drill of the present invention when the tip tool member contacts the workpiece during rotational impact and is being machined, and FIG. 2 is a sectional view of the tip tool member being machined from the state shown in FIG. 1. FIG. 3 is a cross-sectional view of the main part in a state separated from the member, and FIG. 3 is a cross-sectional view of the main part in a state in which the tip tool member is changed from the state shown in FIG. 1 to a rotary-only one. 6... Cylinder, 7... Cylinder case, 10... Tool holder, 12... Intermediate, 15... Tip tool member, 17・・・・・・
- Striker, 18... Piston, 20.21...
...Vent, 22...Air chamber.

Claims (1)

[Claims] 1. A cylinder that is driven to rotate once within a cylinder case via a drive source and stores a striking element therein to form an air chamber;
A piston is slidably attached within the cylinder and driven by the drive source, and a tip tool member is detachably attached and driven to rotate integrally with the cylinder, and is slidable a predetermined distance in the axial direction and displaced toward the tip side. A tool holder that is pressed and attached via a spring and driven reciprocally via the piston, and a vent hole of the air chamber formed at a position that communicates with the air chamber when the tool holder is stopped and is blocked via the striker when the tool holder is retracted. In the tool holder, an intermediate element is formed to be slidable a predetermined distance between the striking element and the tip tool member on the inner periphery of the tool holder, and the intermediate element is attached to the tool holder and the air is supplied through the striking element when the tool holder is retracted. An electric hammer drill characterized in that it is possible to attach a tip tool member having a shortened length of the shank portion that contacts the meson and a tip tool member whose length is not shortened so that the ventilation hole of the chamber is not blocked.