JPH0422934Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial field of application) This invention relates to impact tools such as hammer drills used for chipping work such as concrete.

(Prior Art) In conventional impact tools, the state in which the bit is inserted into the barrel is locked by, for example, a lock plate attached to the front end of the barrel.

(Problems to be solved by the invention) In the impact tool equipped with the lock plate described above, when an external force such as an impact action is applied to the lock plate, the lock plate may be deformed or incorrectly rotated in the direction of releasing the bit due to the external force. There was a problem in which the lock state for the bit was erroneously released.

It is an object of the present invention to provide a striking tool with protective means capable of protecting the lock plate from external forces.

(Means for Solving the Problems) In the impact tool of the present invention, a cover member made of an elastic material is provided around the front end of a cover member of an elastic material that covers a barrel which is equipped with an internal impact mechanism for impacting a bit. In order to lock the inserted state of the lock plate, a lock plate is vertically rotatably mounted, and an impact protrusion is formed in a circumferential shape and protrudes from the outer periphery of the lock plate.

(Function) The present invention is characterized in that the outer peripheral edge of the lock plate attached to the front end surface of the barrel of the impact tool is opposed to a gentle collision strip that is protruded near the front end of the cover member that covers the barrel. It is constructed to receive external force applied to the lock plate.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings. In the drawing, 1 is a cylindrical barrel placed horizontally on the upper end of the impact tool main body H, and a motor (not shown) is connected to the barrel. A head portion 1a is connected to the upper front end of the housed motor housing 2, and a step-like head portion 1a having a hexagonal shaft hole 3 is formed at the front end.

Reference numeral 4 denotes a cylinder fitted so as to be slidable in the front-rear direction inside the barrel 1, which is tightly fitted near the front part of the barrel 1 and the head part 1a, and has a first stepped part 4a formed near the front end thereof. contacts the head portion 1a of the barrel 1, and the third stepped portion 4c formed near the rear end contacts the retaining ring 5 fitted to the upper end of the motor housing 2, thereby defining the movement range. A locking surface 4d is formed in a conical shape on the inner peripheral surface near the center, and a locking surface 4d is arranged behind the locking surface 4d so that the inside of the cylinder 4 communicates with the outside air at the rearward end of the cylinder 4. A relief hole 4e provided, a striking hole 4f having a smaller diameter than the relief hole 4e, and an air distribution hole 4g are provided in order from the front.

Reference numeral 6 denotes a spring interposed between the second stepped portion 4b at the front of the cylinder 4 and the stepped portion 1b at the front of the barrel 1 in order to always bias the cylinder 4 rearward.

A piston 7 is tightly fitted in the vicinity of the rear end of the cylinder 4 so as to be able to reciprocate back and forth, and a crank 8 is rotatably suspended within the motor housing 2.
is connected to the crank pin 8a via a connecting rod 9.

Reference numeral 10 denotes a first hammer that is slidably and tightly fitted into the rear part of the cylinder 4, and has a conical engagement surface 10a on its outer peripheral surface near its front end for engagement with the locking surface 4d of the cylinder 4. The first hammer 10 is formed to be releasable, and when the cylinder 4 moves forward, the first hammer 10 is pushed forward by the compression effect on the air in the rear air chamber 11B formed behind the first hammer 10 in the rear part of the cylinder 4. While moving forward, when the piston 7 retreats, the front air chamber 11A formed in front of the first hammer 10 is communicated with the outside air, and the first hammer 10 moves rearward due to the depressurization effect on the air in the rear air chamber 11B. It is attracted and moves back together with the piston 7.

Reference numeral 12 denotes a bit that is fitted near the front end of the barrel 1, and the shank portion 12a at the rear end is slidable and penetratingly fitted into the shaft hole 4b at the front end of the cylinder 4. A continuous front hexagonal flange portion 12b is slidably but unrotatably fitted into the shaft hole 3 of the head portion 1a of the barrel 1.

Bit 13 indicates the advancing operation of the first hammer 10.
A second hammer is inserted between the first hammer 10 and the bit 12 so as to be slidably fitted tightly into the cylinder 4 in order to transmit the information. A pair of keys 14, 14 inserted in the radial direction are inserted into the second
The movement range of the hammer 13 is defined and the second hammer 1 is
A pair of keyways 13a,
13a is recessed along the axial direction. Then, when the piston 7 is driven with the bit 12 in pressure contact with the processing surface, the first hammer 10 hits the second hammer 13 in the retreated position and then rebounds over the hitting hole 4f of the cylinder 4 due to the reaction from the hitting. As the piston 7 moves backward, it returns to the backward end due to the suction action accompanying the backward movement of the piston 7. Therefore, each time the piston 7 moves back and forth, the bit 12 receives the impact action of the first hammer 10 via the second hammer 13. transmitted repeatedly. on the other hand,
In an unloaded state in which the bit 12 is separated from the machining surface or in an unloaded state in which the bit 12 is not inserted, the piston 7 is actuated to move the first hammer 10 to the first
The hammer 10 is advanced to the forward end position where the engaging surface 10a and the locking surface 4d of the cylinder 4 are in contact with each other, and the second
When the hammer 13 is held at the forward end position, the first
The engagement surface 10a of the hammer 10 is the locking surface 4 of the barrel 1.
d and is held incapable of idle firing at the forward end position, or it rebounds and retreats from the forward end due to poor engagement between the engaging surface 10a and the engaging surface 4d.

When the first hammer 10 rebounds and retreats, the cylinder 4 is pressed by the first hammer 10 and moves forward against the spring 6, closing the relief hole 4e and sealing the front air chamber 11A. A suction action is applied to the hammer 10 by the back pressure of the front air chamber 11A, and the amount of the first hammer 10 to retreat is limited, and the first hammer 10 retreats slightly within a range that does not exceed the striking hole 4f. The released cylinder 4 moves backward by the elastic force of the spring 6.

Furthermore, in this state, the piston 7 operates and the first
Even when the hammer 10 moves forward and backward, the inside of the rear air chamber 11B is communicated with the outside air through the striking hole 4f and the air pressure is reduced. A pressing force of 10 is transmitted to the spring 6 via the cylinder 4 and buffered.

Therefore, even when the first hammer 10 repulses and retreats, the idle striking action of the first hammer 10 is reduced and impact on the cylinder 4 and barrel 1 is suppressed.

Reference numeral 15 denotes a lock plate that is vertically rotatably attached to the front end surface of the head portion 1a of the barrel 1 to lock the inserted state of the bit 12, and is formed to allow the bit 12 to pass through. A bolt 16A that passes through one side of the plate 15 and is screwed into the head portion 1a allows the lock plate 15 to rotate upward with the bolt 16A as a fulcrum relative to the other side of the lock plate 15. It is attached to the front end surface of the head part 1a through a bolt 16B that is screwed into the head part 1a through a long hole 15a, and its outer peripheral edge 15b surrounds the front end edge of the barrel 1. At the same time, the body 12 of the bit 12 is located near the center of the bend.
The upper hole 15c has a circular shape for slidably inserting the lock plate 15, and the flange portion 12 of the piston 12 with the lock plate 15 rotated upward.
Hexagonal hole 1 for inserting b.
5d are arranged vertically in a partially polymerized state,
Further, a spherical locking piece 18 fitted into the front end of the head portion 1a and urged forward by a spring 17 is removably engaged on the back surface near the upper end of the lock plate 15 to secure the lock plate 15 to the body of the bit 12. An engagement hole 15e is formed for locking the portion 12c in the lock position where the portion 12c is fitted into the upper hole 15c of the lock plate 15.
When the lock plate 15 is held in the lock position, the bit 12 is prevented from coming off.

Reference numeral 19 denotes a cover member that tightly fits over almost the entire length of the barrel 1, and is formed of an elastic material such as rubber into a substantially cylindrical shape. In order to buffer external forces, a gentle collision strip 20 is provided on the outer circumferential edge 15, and is protruded opposite to the outer circumferential edge 15b of the lock plate 15 and has a contour that almost matches the contour of the outer circumferential edge 15b.
It is formed in a circumferential shape along b.

Next, the operation and effects of the embodiment having the above configuration will be explained.

Now, in this example, near the front end of the cover member 19 made of an elastic material that covers the barrel 1, a bit is attached so as to be rotatable perpendicularly to the front end surface of the barrel 1 in order to lock the inserted state of the bit 12. 12, the outer peripheral edge 15b of the lock plate 15 is formed to be penetrable.
A gentle collision strip 20 is formed in a circumferential shape and protrudes so as to face each other.

Therefore, even if crushed pieces or the like fall and collide with the lock plate 15 during work, or even if the impact action of another object is applied to the lock plate 15, these external forces are relaxed and absorbed by the gentle collision strips 20, and the lock plate 15 is Deformation and incorrect rotation can be suppressed, and the lock plate 15 can be accurately protected from external forces to prevent the bit 12 from moving forward or backward, inserting or removing the bit 12 from the barrel 1, or rotating the lock plate 15. This has the effect of preventing troubles in which the lock plate 15 is disturbed due to deformation of the lock plate 15 or the lock state of the bit 12 is erroneously released.

(Effect of the invention) That is, in the present invention, a cover member made of an elastic material that covers a barrel that is equipped with a striking mechanism for striking a bit has a cover member near the front end that locks the inserted state of the bit against the front end surface of the barrel. In order to protect the lock plate from external forces, the lock plate can be accurately protected from external forces by deforming the gentle collision strips, which are protruded from the outer periphery of the lock plate, which is vertically rotatably mounted, into a circumferential shape. This has the effect of preventing malfunctions of bits and lock plates.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional view of the main parts of the impact tool, and FIG. 2 is a view taken along the line X--X in FIG. 1. DESCRIPTION OF SYMBOLS 1... Barrel, 12... Bit, 15... Lock plate, 15b... Outer periphery, 19... Cover member, 20... Gentle collision strip.

Claims (1)

[Scope of utility model registration request] A cover member made of an elastic material is attached to the front end of the barrel which houses a striking mechanism for striking the bit so as to be vertically rotatable in order to lock the inserted state of the bit against the front end surface of the barrel. A striking tool characterized in that a gentle collision strip is formed in a circumferential shape, protruding from the outer periphery of the lock plate.