TW201842992A - Compressed-air-driven chisel - Google Patents

Abstract

Provided is a compressed-air-driven chisel whereby the diameter of a needle holder can be reduced. In the present invention, an annular recess (22a) for backward movement driving is provided on an outer circumferential surface of a needle holder (22) provide in a cylinder so as to be able to move in an axial direction, and compressed air is supplied to a backward movement drive chamber (26) via the annular recess (22a) for backward movement driving when the needle holder (22) is moved forward.

Description

Pressurized air-driven chisel

The present invention relates to a pressurized air-driven chisel driven by pressurized air.

A pressurized air-driven chisel has a piston, an anvil, and a needle clamp installed in the cylindrical member in the axial direction of the cylindrical member, from the rear to the front, and sequentially slidable relative to the cylindrical member. The needle holder holds a needle (needle chisel) extending forward. When the pressurized air is supplied to the forward drive chamber formed at the rear of the piston, the piston is driven forward to hit the rear of the anvil, the anvil is driven forward, and the anvil is pushed to drive the needle clamp forward. In addition, when the needle clamp is driven forward, the pressurized air in the forward drive chamber is exhausted to the outside, and pressurized air is supplied to the backward drive chamber formed on the front end side of the needle clamp, so that the needle clamp Device, anvil and piston back. The needle clamp is driven forward to perform the required operations such as striking the front end of the needle and chiseling the work site.

The needle clamp of the pressurized air-type chisel as described above includes a large-diameter clamp body that seals and engages the inner peripheral surface of the cylindrical member and can slide in the axial direction, and extends coaxially from the clamp body to the front. A small-diameter cylindrical extension that seals and engages the inner peripheral surface of the front end opening of the cylindrical member and is slidable in the axial direction. The jig main body has a ring-shaped front end surface formed around the rear end of the cylindrical extension portion at a front end thereof, and the backward drive chamber is an inner peripheral surface of a cylindrical member that accommodates a needle clamp, a rear side opening of the front end, and a cylinder. The peripheral surface of the elongated portion and the annular front end surface of the jig body are divided.

In the conventional pressurized air-driven chisel as described above, most of the needle holding holes that connect a plurality of needles in the front-rear direction to the clamp body are provided around the center of the radial direction of the clamp body, and are provided near the peripheral surface of the clamp body. The holding holes extend in parallel to the annular front end surface of the jig body and supply a plurality of axial direction passages for supplying pressurized air to the backward drive chamber (see Patent Documents 1 and 2). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2006-289607 [Patent Document 2] Japanese Shiko Sho 62-16295

[Problems to be Solved by the Invention]

As described above, the pressurized air-driven chisel disclosed in the above-mentioned patent document is provided in the vicinity of the peripheral surface of the jig main body with the axial direction hole for pressurized air facing the drive chamber being opened at the annular front end surface of the jig main body. The needle gripper repeats the reciprocating motion violently by the impact of the piston as described above. Therefore, the wall thickness from the hole in the axial direction to the peripheral surface of the main body of the clamp must be sufficient to withstand this severe reciprocating motion. A limiting factor when the compressed air driven chisel is miniaturized and the outer diameter of the needle clamp must be reduced.

The present invention has been made in view of the foregoing points, and it is an object of the present invention to provide a pressurized air-driven chisel capable of making the outer diameter of the needle clamp smaller than a conventional one. [Means for solving problems]

The pressurized air-driven chisel according to the present invention includes: a cylinder having a rear-end closed member provided at the rear end and a front-end cylindrical member provided at the front end of the front-end opening; and a movable element included in the cylinder. The cylinder slides in the axial direction to hold a needle clamp that extends a plurality of needles forward from the front end opening and a movable element of a piston arranged at a rear position of the needle clamp. The piston introduces pressurized air into the piston. The forward drive chamber formed at the rear of the piston is thereby driven forward to apply a striking force to the needle clamp from the rear to the front. The needle clamp has a sealing engagement on the inner peripheral surface of the cylinder and can be A large-diameter clamp body that slides in the axial direction, and a small-diameter cylindrical portion that extends forward from the clamp body and is tightly engaged with the inner peripheral surface of the front-end cylindrical member and can slide in the axial direction. It has a ring-shaped front end surface whose front end is formed around the rear end of the cylindrical portion, and a through hole which accommodates the needle so as to extend inside the cylindrical portion in the front-rear direction. The needle holding hole in the line direction, the needle clamp is driven forward by the striking force of the piston, and can be displaced until the annular front end surface abuts the front end position of the rear end of the front cylindrical member. The inner peripheral surface extends rearward from the position of the rear end of the front end cylindrical member toward the axial direction and has a larger diameter than the outer peripheral surface of the clamp body, and a compartment having a partitioned back drive chamber is formed between the outer peripheral surface of the clamp and the needle clamp. Zoned recesses; and a pressurized air supply path having a forward drive path for supplying pressurized air to the forward drive chamber and a backward drive path for the reverse drive chamber, through the forward drive path and the backward drive path The pressurized air is alternately supplied to the forward drive chamber and the backward drive chamber. The pressurized air supply path includes a cylinder which is slidably engaged with an outer peripheral surface of the jig body through the cylinder. Cylinder path for backward driving which is opened on the inner peripheral surface of the cylinder, and the inner peripheral surface of the cylinder which is slidably engaged with the outer peripheral surface of the clamp body and the outer peripheral surface At least one of the backward driving communication recesses extending in the axial direction and communicating with the backward driving cylinder passage is provided. When the needle clamp is located at the front end position, the backward driving communication recesses communicate with the backward driving chamber. Compressed air is supplied to the backward drive chamber.

The pressurized air-driven chisel according to the present invention does not, as is conventionally, set the passage for communicating the opening of the cylinder path for backward driving with the backward driving chamber when the needle clamp is located at the front end position on the periphery of the needle clamp. The vicinity of the surface serves as an axial direction hole, and is a recessed portion (recession driving communication recessed portion) provided in at least one of the peripheral surface of the jig main body and the inner peripheral surface of the cylinder slidably engaged with the peripheral surface in the axial direction. Therefore, when the above-mentioned axial direction holes are provided, it is not necessary to increase the wall thickness from the axial direction holes to the outer surface of the clamp body in order to maintain the strength of the needle clamp, and the flow path required for supplying pressurized air is required. The cross-section can be obtained with a recessed portion having an extremely small depth compared with the diameter dimension of the axial direction hole when the cross-section is provided as an axial direction hole in the needle clamp. Therefore, the pressurized air-driven chisel of the present invention can greatly reduce the diameter of the needle clamp compared with the conventional one.

A specific example of the backward driving communication recess is formed on the peripheral surface of the jig body, and a portion between a front end of the peripheral surface of the jig main body and an axial direction front end of the backward driving communication recess is with the cylinder. The inner peripheral surface is hermetically engaged, preventing communication with the backward drive chamber of the backward drive communication recess.

More specifically, the backward driving communication recessed portion may be formed as an annular recessed portion extending in a peripheral direction of the peripheral surface of the clamp body.

The recessed driving recess may be provided on the outer peripheral surface of the jig main body or in addition to the recessed portion formed on the inner peripheral surface of the cylinder and extending through the opening of the cylinder path for the recessed driving and the chamber partition recess. The sealing convex part which is intermittently provided with the outer peripheral surface of the jig main body and which is engaged with the backward driving communication recess and which can slide further in front of the opening of the backward driving cylinder passageway than the backward driving communication recess is provided. The sealing convex portion is separated from the backward driving communication recessed portion when the needle clamp is at the front end position, and the backward driving cylinder passage can be communicated with the chamber division concave portion through the backward driving communication recessed portion.

The needle holding hole has a needle head receiving portion that sequentially expands in diameter from the vicinity of the rear end of the needle holding hole toward the rear end surface of the clamp body. The needle head receiving portion is adapted to receive a protrusion from the needle head receiving portion to the rear. The head of the rear end of the needle inserted into and held by the needle holding hole may be provided on the rear end face of the needle clamp with a ring shape protruding further rearward than the head of the protruding needle along its periphery. Protrusion. It is easy to narrow the space between the needles. At this time, the head of the needle may have a side surface which is sequentially widened toward the rear corresponding to the needle head receiving portion.

Specifically, has a cylindrical housing for accommodating the cylinder coaxially, and has an axial direction extending between the outer peripheral surface of the cylinder and the inner peripheral surface of the housing to be introduced into the housing. The pressurized air supply path through which the pressurized air passes along the outer peripheral surface of the cylinder, and the cylinder path for backward driving may pass through the cylinder in a radial direction and communicate with the pressurized air supply path.

The pressurized air supply passage may be a cylindrical passage formed between the cylinder and the housing.

The movable element has an anvil that is displaceable in the axis direction between the piston and the pincer, and the anvil is driven forward by the piston driven forward to transmit the striking force from the piston. To the needle clamp, the needle clamp has an exhaust passage that runs through the center of its diameter in the axial direction, and the exhaust passage communicates with the forward drive chamber when the needle clamp reaches the front end position. Pressurized air is discharged to the front and outside of the needle clamp.

The needle further has a needle, which is held in the needle holding hole and is respectively displaceable in the axial direction and extends forward from the needle clamp toward the axial direction and extends forward from the front end opening of the cylinder. The rear side of the rear end of the part receiving part which protrudes rearward in order to reduce the diameter in the front so that the side can abut the surface of the needle head receiving part.

Hereinafter, a pressurized air-driven chisel according to the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, the pressurized air-driven chisel 10 according to the present invention includes a plurality of needles (needle chisels) 12 (six needles in the figure), and passes through the air introduction hole at the rear end of the pressurized air-driven chisel 10 The pressurized air introduced from a pressurized air supply pipe (not shown) connected to 11 (FIG. 2) drives the needle 12 as a whole forward and backward, and strikes the work site with its tip to perform work such as chiseling.

As shown in FIG. 2, the pressurized air-driven chisel 10 includes a cylindrical case 14 and a cylinder 16 coaxially mounted in the case 14. The pressurized air-driven chisel 10 further includes a piston 18, an anvil 20, and a needle clamp 22 that are sequentially mounted in the cylinder 16 in the axial direction from the front to the rear. The needle clamp 22 keeps each needle 12 extending forward from the front end opening 17 of the needle clamp 22. In the example shown in the figure, the casing 14 is composed of a casing rear portion 14a and a casing front portion 14b connecting the casing rear portion 14a. The cylinder 16 is composed of: a cylindrical cylinder body 16a; a rear end closing member 16b installed at the rear end of the cylinder body 16a and closing the rear end; and a front end of the cylinder body 16a extending forward and dividing the front opening 17 The front end cylindrical member 16c is configured.

A forward drive chamber 24 is formed in the cylinder 16 between the piston 18 and the rear-end closing member 16b (Figs. 2, 4, and 6), and a retreat is formed between the needle clamp 22 and the front-end cylindrical member 16c. The driving chamber 26 communicates with the air introduction hole 11 through a valve 28 provided at the rear portion 14a of the housing, and passes through a cylindrical pressurized air supply passage 30 extending between the inner peripheral surface of the housing 14 and the outer peripheral surface of the cylinder 16. The pressurized air is alternately supplied to the forward drive chamber 24 and the backward drive chamber 26.

Specifically, the pressurized air supply passage 30 includes a rear passage portion 30 a that communicates with the forward drive cylinder passage 16 d provided in the radial direction near the rear of the cylinder 16, and extends forward from the rear passage portion 30 a in the cylinder. Near the front of 16, a forward passage portion 30 b communicating with the backward drive cylinder passage 16 e provided in the radial direction is penetrated. The piston 18 has a small-diameter portion 18a provided on a peripheral surface thereof extending from a position near the rear to a front end position, and a large-diameter portion 18b on the rear side of the small-diameter portion 18a. The small-diameter portion 18 a and the large-diameter portion 18 b are partially sealed with a diameter corresponding to each of the inner peripheral surface of the cylinder 16 so as to be slidable. The small-diameter portion 18a is provided with a forward-drive radial direction passage 18d penetrating in the diameter direction. A forward-drive axial direction communicating with the forward drive chamber 24 is provided from the forward-drive diameter passage 18d to the rear end face of the piston 18. Path 18c. The pressurized air passing through the forward drive cylinder passage 16d passes through the space 32 formed between the inner peripheral surface of the cylinder 16 and the small diameter portion 18a when the cylinder 16 is at the rear end position shown in FIG. 2 and the forward drive diameter. The directional passage 18d and the forward drive axial passage 18c are supplied to the forward drive chamber 24. The backward drive cylinder passage 16e is capable of supplying pressurized air to the backward drive annular recess 22a (FIG. 7) provided on the outer peripheral surface of the needle clamp 22 when the needle clamp 22 is driven forward. Backward drive chamber 26. Specifically, the needle clamp 22 includes a large-diameter clamp body 22b that is slidably engaged with the inner peripheral surface of the cylinder 16 and a seal body that extends forward from the clamp body 22b and is sealingly engaged with the front end cylindrical member 16c. A small-diameter cylindrical portion 22c that is slidable on the peripheral surface. The jig main body 22b has a ring-shaped front end surface 22d formed at the front end around the rear end of the cylindrical portion 22c. When the needle clamp 22 is driven forward by the anvil 20, it can be displaced to the ring-shaped front end surface 22d to abut. To the front end position of the rear end of the front end cylindrical member 16c. The aforementioned recessed driving annular recessed portion 22 a is provided on the outer peripheral surface of the clamp body 22 b at an intermediate position separated from the front end and the rear end thereof. The inner peripheral surface of the cylinder 16 extends rearward from the position of the rear end of the front end cylindrical member 16c toward the axial direction and has a larger diameter than the outer peripheral surface of the clamp body 22b. The chamber portion 16f of the chamber 26 is recessed. When the needle clamp 22 is driven forward (FIG. 6 and FIG. 7), the annular recessed portion 22a for backward driving is communicated with the backward driving chamber 26, and pressurized air is supplied to the backward driving chamber 26.

The needle clamp 22 includes a needle holding hole 22e penetrating the clamp body 22b in the front-rear direction and holding the needle 12, and an exhaust passage 22f penetrating the center of the cross-section of the clamp body 22b in the front-rear direction. The needle holding hole 22e is provided with a needle head receiving portion 22g having an inclined surface 22h which is gradually enlarged in diameter from the vicinity of its rear end toward the rear end surface of the clamp body 22b, and the needle 12 includes a side surface 12a corresponding to the inclined surface 22h of the needle head receiving portion 22g. The needle head 12b. In a state where the needle head portion 12b is received by the needle head receiving portion 22g, the side surface 12a of the needle head 12b abuts the inclined surface 22h of the needle head receiving portion 22g, so that the rear end of the needle head 12b protrudes rearward from the needle head receiving portion 22g. . The rear end surface of the needle clamp 22 has a ring-shaped projection 22j protruding further rearward than the needle head 12b protruding rearward from the needle-head receiving portion 22g along the peripheral edge thereof. The anvil 20 passes through the ring-shaped projection 22j. Forward driving force is transmitted to the needle clamp 22. The needle 12 receives the needle head portion 12b on the needle head receiving portion 22g as described above, thereby integrating with the needle holding hole 22e, making the needle 12 less prone to trembling.

When the pressurized air-driven chisel 10 is in a state where no pressurized air shown in FIG. 2 is introduced, the operating lever 34 supported by the shaft at the rear portion 14a of the housing is lowered to open the valve 28, so that the pressurized air is as The rear passage portion 30a, the forward drive cylinder passage 16d, the forward drive diameter passage 18d, and the forward drive axial passage 18c, which are transmitted through the pressurized air supply passage 30, are supplied to the forward drive chamber 24. As the piston 18 is driven forward, the anvil 20 is hit from the rear by a striking protrusion 18e provided at the front end thereof (FIGS. 4 and 5). In this state, the forward drive diameter passage 18d extending from the forward drive chamber 24 is in a state of communicating with the space 35 formed on the rear side of the anvil 20, and pressurizes the forward drive chamber 24 that drives the piston 18 forward. The air communicates with the space 36 between the front end surface of the anvil 20 and the rear end surface of the needle holder 22 through the axial hole 20a provided in the anvil 20, and is exhausted through the exhaust passage 22f of the needle holder 22 to external. At this time, the ring-shaped recessed portion 22 a for backward drive of the peripheral surface of the jig body 22 b is not yet in communication with the backward drive chamber 26, and no pressurized air is supplied to the backward drive chamber 26. When the needle clamp 22 is driven forward, the volume of the backward driving chamber 26 is reduced, but the air in the backward driving chamber 26 is discharged to the radial exhaust hole 22i provided in the cylindrical portion 22c of the needle clamp 22 to Outside, the needle clamp 22 can be advanced substantially without resistance from the air pressure in the backward drive chamber 26.

By driving the anvil 20 that is struck from the rear by the piston 18 forward, the needle clamp 22 is driven forward, so that the needle clamp 22 is in the front end position that conflicts with the front end cylindrical member 16c (Figures 6 and 7). . In this state, the annular recess 22a for backward driving communicates with the backward driving chamber 26, supplies pressurized air to the backward driving chamber 26, and starts driving the needle clamp 22 to the rear. When the anvil 20 and the piston 18 are returned to the state shown in FIG. 2 by the needle clamp 22, the piston 18 is again driven forward by pressurized air. In this way, the reciprocating movement of the needle clamp 22 is repeated, and the striking operation is performed on the work site by the needle 12.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this. For example, in the embodiment described above, in order to communicate the backward drive cylinder passage 16e with the backward drive chamber 26 when the needle clamp 22 is driven forward, it is performed by the backward drive annular recess 22a provided on the outer peripheral surface of the clamp body 22b. However, the ring-shaped recessed portion for the reverse driving may be provided on the inner peripheral surface of the cylinder 16 so as to extend between the cylinder path 16e and the recessed portion 16f for the recessed driving. At this time, a sealing protrusion is provided on the outer surface of the clamp body 22b to engage and seal the backward driving communication recessed portion, and the forward driving cylinder passage 16e can slide forward in the backward driving communication recessed portion. The needle clamp 22 faces When the front end position is driven, the sealing convex portion is separated from the forward drive communication recessed portion to the front, so that the backward drive cylinder passage 16e and the chamber division concave portion 16f can be communicated by this. In addition, although the cylinder body, the rear-end closing member, and the front-end cylindrical member are shown separately, they may be integrally formed.

10‧‧‧ pressurized air-driven chisel

11‧‧‧air inlet

12‧‧‧ Needle (Needle Chisel)

12a‧‧‧side

12b‧‧‧Head

14‧‧‧shell

14a‧‧‧Rear of the housing

14b‧‧‧Front of housing

16‧‧‧ Cylinder

16a‧‧‧Cylinder body

16b‧‧‧back end closed member

16c‧‧‧Front end cylindrical member

16d‧‧‧Cylinder passage for forward drive

16e‧‧‧ Cylinder passage for backward drive

16f‧‧‧Room divisions

18‧‧‧ Pistons

18a‧‧‧ Trail

18b‧‧‧large diameter section

18c‧‧‧Axial passage for forward drive

18d‧‧‧Forward drive diameter path

18e‧‧‧ Strike

20‧‧‧ Anvil

20a‧‧‧Axial hole

22‧‧‧ Needle clamp

22a‧‧‧ Reverse drive ring recess

22b‧‧‧fixture body

22c‧‧‧Tube

22d‧‧‧ annular front surface

22e‧‧‧ Needle holding hole

22f‧‧‧Exhaust passage

22g‧‧‧ Needle head receiving part

22h‧‧‧inclined

22i‧‧‧ Radial vent

22j‧‧‧ annular protrusion

24‧‧‧ Forward Drive Room

26‧‧‧Backward drive room

28‧‧‧ Valve

30‧‧‧ Pressurized air supply path

30a‧‧‧ Rear access section

30b‧‧‧Front access section

32‧‧‧ space

34‧‧‧ Joystick

35, 36‧‧‧ space

FIG. 1 is a perspective view of a pressurized air-driven chisel according to an embodiment of the present invention. Fig. 2 is a longitudinal sectional view of a state where the pressurized air-driven chisel of Fig. 1 is not driven. FIG. 3 is an enlarged view of a part of the longitudinal sectional view of FIG. 2. Figure 4 is the same as Figure 2, but shows a state where pressurized air is introduced into the forward drive chamber and the piston advances to hit the anvil. Fig. 5 is an enlarged view of a part of the longitudinal sectional view of Fig. 4. Figure 6 is the same as Figure 2, but shows the state when the needle clamp reaches the tip position. FIG. 7 is an enlarged view of a part of the longitudinal sectional view of FIG. 6.

Claims (9)

A pressurized air-driven chisel having: a cylinder having a rear end closing member provided at a rear end and a front end cylindrical member provided at a front end opening opening; a movable element including an axis of the cylinder that is accessible to the cylinder Slide in the direction to keep the needle clamp that extends the plurality of needles forward from the front opening and the movable element of the piston arranged at the rear position of the needle clamp. The piston is formed by introducing pressurized air into the cylinder. The forward drive chamber of the rear part of the piston is driven forward to apply a striking force to the needle clamp from the rear to the front. The needle clamp has a sealing engagement with the inner peripheral surface of the cylinder and can be on the axis. A large-diameter clamp body that slides in a direction and a small-diameter cylindrical portion that extends forward from the clamp body and is tightly engaged with the inner peripheral surface of the front-end cylindrical member and can slide in the axial direction. : A ring-shaped front end surface whose front end is formed around the rear end of the cylindrical portion, and a through-axis line that accommodates the needle so that the inside of the cylindrical portion extends in the front-rear direction The needle clamp is driven forward by the striking force of the piston and can be displaced to the forward end position where the annular front end surface abuts the rear end portion of the front end cylindrical member. The peripheral surface extends from the position of the rear end of the front end cylindrical member toward the rear of the axis direction, and has a larger diameter than the peripheral surface of the clamp body, forming a compartment partition with a receding drive chamber between the peripheral surface of the needle clamp. A recessed portion; and a pressurized air supply path having a forward driving path for supplying pressurized air to the forward driving chamber and a backward driving path for supplying the backward driving chamber, and the forward driving path and the backward driving path The pressurized air is alternately supplied to the forward driving chamber and the backward driving chamber. The pressurized air supply path includes a cylinder which is slidably engaged with an outer peripheral surface of the jig body through the cylinder. The cylinder path for backward driving, which is opened on the inner peripheral surface of the cylinder, and the outer peripheral surface of the clamp body and the inner peripheral surface of the cylinder which is slidably engaged with the outer peripheral surface. At least one side is provided with a backward driving communication recessed portion extending in the axial direction and communicating with the backward driving cylinder passage. When the needle clamp is at the front end position, the backward driving communication recessed portion communicates with the backward driving chamber. Compressed air is supplied to the backward drive chamber. The pressurized air-driven chisel according to item 1 of the patent application scope, wherein the back-driving communication recess is formed on the outer peripheral surface of the jig body, and the front end of the outer peripheral surface of the jig main body is connected to the back-driving driver. In a state where a portion between the front ends in the axial direction of the communication recessed portion is sealingly engaged with the inner peripheral surface of the cylinder, communication with the backward driving chamber of the backward driving communication recessed portion is prevented. The pressurized air-driven chisel according to item 2 of the patent application scope, wherein the backward driving communication recess is formed as an annular recess extending in a peripheral direction of the peripheral surface of the clamp body. The pressurized air-driven chisel according to item 1 of the patent application scope, wherein the back-driving communication recess is formed on the inner peripheral surface of the cylinder, and the opening and the chamber extending from the back-driving cylinder passage are formed. Between the divided recesses, the peripheral surface of the jig main body is sealingly engaged with the sealing recesses for the backward driving communication recess and can be slid forward from the opening of the cylinder path for the backward driving sealing recesses, The sealing convex portion is separated forward from the backward driving communication recessed portion when the needle clamp is at the front end position, and the backward driving cylinder passage can be communicated to the chamber division concave portion through the backward driving communicating recessed portion. The pressurized air-driven chisel according to any one of claims 1 to 4 in the patent application scope, wherein the needle holding holes respectively have a distance from the vicinity of the rear end of the needle holding hole toward the rear end surface of the clamp body. A sequentially enlarged needle head receiving portion is provided on the rear end portion of the needle that is inserted through the needle holding hole and held behind the rear end of the needle head to protrude rearward from the needle head receiving portion. The head has, on the rear end surface of the needle clamp, a ring-shaped protrusion that protrudes rearwardly from the head of the protruding needle along its periphery. The pressurized air-driven chisel according to any one of claims 1 to 4 in the scope of patent application, which comprises a cylindrical housing that accommodates the cylinder coaxially, and further includes an outer surface of the cylinder and a cylinder. A pressurized air supply path extending between the inner peripheral surface of the casing and the axial direction to pass pressurized air introduced into the casing along the outer peripheral surface of the cylinder, and the cylinder path for backward driving is in a radial direction. Passes through the cylinder and communicates with the pressurized air supply passage. The pressurized air-driven chisel according to item 6 of the patent application scope, wherein the pressurized air supply passage is a cylindrical passage formed between the cylinder and the casing. The pressurized air-driven chisel as described in any one of claims 1 to 4, wherein the movable element has an anvil provided between the piston and the needle clamp and displaceable in the axial direction. The anvil transmits the striking force from the piston to the needle clamp by driving the piston driven forward from the rear, and the anvil has an exhaust passage that runs through the center of its diameter in the axial direction. The exhaust passage communicates with the forward drive chamber when the needle clamp reaches the front end position and discharges the pressurized air in the forward drive chamber to the outside of the front of the needle clamp. The pressurized air-driven chisel according to item 5 of the scope of patent application, further comprising the needle, each of which is held in the needle holding hole so as to be displaceable in the axial direction and extends from the needle clamp toward the axial direction forward from the needle holder. The front end opening of the cylinder extends forward, and the head portion has side surfaces that are sequentially reduced in diameter from the rear end that protrudes rearward from the needle head receiving portion, so that the side surface abuts the surface of the needle head receiving portion. .