JP2556439Y2 - Weight piston structure in pneumatic impact mechanism - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a driving piston which is slidably housed in a driving cylinder and is arranged opposite to a driving piston driven by pneumatic pressure. When the driving piston is driven, a reaction force generated as a reaction of the piston is generated. The present invention relates to a structure of a weight piston which is slidably housed in an impact tool for absorption.

[0002]

2. Description of the Related Art A drive piston housed in a drive cylinder fixedly arranged in a housing is driven by compressed air in an impact manner, and a fastener such as a nail is driven into a material to be driven by a driver connected to the drive piston. Pneumatically driven nailers are already known. In the impact mechanism used in this type of nailing machine or the like, the compressed air introduced into the drive cylinder drives the drive piston downward and simultaneously acts on the inner wall surface at the upper end of the drive cylinder to raise the drive cylinder upward. A reaction force to move the This reaction force causes the tool housing to move in the direction opposite to the direction of impact, causing problems such as loss of driving force.

[0003] The applicant uses the reaction force of the drive piston transmitted to the tool housing in the above-mentioned conventional impact mechanism to actuate a weight piston, which is arranged to be able to be impulsively arranged on the drive axis of the drive piston, in a direction opposite to the drive piston. Thus, an impact mechanism has been proposed in which the reaction force is offset to prevent the upward reaction force from being transmitted to the tool housing (Japanese Patent Application No. 04-91519). In the above proposal, the weight piston diameter is set to be larger than the drive piston diameter, and a part of the reaction force of the weight piston is caused to act on the housing in the drive direction of the drive piston. To prevent the housing from jumping up.

[0004]

By the way, since the compressed air for driving the driving piston is simultaneously applied to the weight piston to operate both pistons in opposite directions, the working stroke of both pistons is provided in the housing of the tool. Minute dimensions are required. Usually, the weight piston is disposed above the driving piston, and therefore, the height dimension of the tool is not easily designed. When the operating stroke of the drive piston is constant, the stroke length of the weight piston is determined by the ratio of the weight of the drive piston to the weight of the weight piston, and the stroke becomes smaller as the weight of the weight piston becomes larger than the weight of the drive piston. Can do things. On the other hand, since the outer diameter of the weight piston is determined by the outer diameter of the drive piston, it is not possible to increase the outer diameter to increase the volume of the weight piston. If the height is to be increased, the height of the weight piston itself must be increased, and as a result, the height of the impact tool cannot be reduced. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a weight piston of an impact mechanism which can design the height of the impact mechanism itself to be small.

[0005]

According to the present invention, there is provided a drive cylinder fixedly arranged in a housing of a tool, and a drive piston slidably housed in the drive cylinder. An impact mechanism for driving the drive piston by introducing compressed air to the upper surface of the drive piston in the drive cylinder, the drive mechanism having a downward effective surface facing the upper chamber of the drive piston of the drive cylinder, and A weight piston slidably arranged in the operating axis direction of the drive piston, wherein at least a part of the weight piston is made of a high specific gravity metal. Further, the weight piston is characterized in that a core material made of a metal having a high specific gravity is enclosed in a piston main body formed in a hollow shape of iron, aluminum or the like. Further, the weight piston is divided into a plurality in the axial direction, and at least one of the weight pistons is made of a high specific gravity metal.

[0006]

According to the present invention, when the driving piston is driven by the compressed air pressure, the weight piston is driven in the opposite direction to the driving piston by the same compressed air pressure, so that the reaction force generated in association with the driving of the driving piston. It is possible to prevent the reaction force generated by driving the drive piston from being generated in the housing, and the weight piston is made of high specific gravity metal, so the weight of the weight piston per volume can be increased. The operating stroke of the weight piston can be reduced while the piston is operating, and the height of the weight piston itself with the same outer diameter can be designed to be small.

[0007]

[Effects of the Invention] The height dimensions of the weight piston itself and the stroke length of the weight piston can be designed to be small, so that the height dimensions of a nailing machine or the like employing an impact mechanism can be reduced, for example, the size of a tool such as a nailing machine can be reduced. -It is possible to reduce the weight.

[0008]

FIG. 1 shows an embodiment in which the impact mechanism of the present invention is applied to a nailing machine. A main chamber 13 for forming an outer shell of a nailing machine 10 and storing compressed air in a grip portion 12 is shown. A drive cylinder 14 is fixedly arranged in the housing 11 formed with the above. A drive piston 15 to which a driver 16 is connected is slidably accommodated in the drive cylinder 14 toward the lower surface side. The housing 11
A nose member 17 is fixed to a lower portion of the nose member for guiding a driver 16 slidably connected to the drive piston 15. The nose member 17 is interconnected from a magazine (not shown) in the nose member 17. The nails are sequentially supplied. A bumper 18 is disposed on the bottom surface of the housing 11 that supports the lower end of the drive cylinder 14 to buffer and stop the impact force of the drive piston 15.

A cylinder cap 19 is disposed in the shape of the housing 11 so as to close an opening of the housing 11, and a sub-cylinder 20 having an inner diameter larger than the inner diameter of the drive cylinder 14 is provided inside the cylinder cap 19.
Are formed coaxially with the drive cylinder 14, and a weight piston 21 is slidably disposed in the sub-cylinder 20. The weight piston 21 is constantly urged to the bottom dead center position by a compression spring 22 interposed between the weight piston 21 and the upper wall surface of the cylinder cap 19. A piston stop 23, which is held between the upper end of the drive cylinder 14 and the lower end of the sub-cylinder 20 and stops the drive piston 15 at the top dead center position and the weight piston 21 at the bottom dead center position, is arranged. On the lower surface side of the piston stop 23, there is formed a piston holding portion 23 'which engages with a projection 15' formed on the upper surface of the drive piston 15 to hold the drive piston 15 at the top dead center position.

An air supply port 24 for introducing compressed air into the drive cylinder 14 or discharging compressed air from the drive cylinder 14 to the outside of the drive cylinder is formed in a cylinder wall at the upper end of the drive cylinder 14. The air supply port 24 is connected to the main chamber 13 and the exhaust port 26 by an annular main valve 25 disposed in an annular gap formed between the outer peripheral surface of the sub cylinder 20 and the inner wall surface of the cylinder cap 19.
And selectively connected to The operation of the main valve 25 is controlled by compressed air pressure in a control chamber 25 ′ in which the upper end face of the valve faces. The control chamber 25 ′ is partially formed at the tip of the manually operated trigger lever 27 or the nose member 17. The air passage 30 is connected to a trigger valve 29 operated by a protruding safety mechanism 28 or the like.

The weight piston 21 is composed of a core member 31 made of a metal having a high specific gravity such as lead or tungsten, and a bottom plate 32 made of a metal such as iron or aluminum. The core member 31 is formed in a thick, substantially cylindrical shape having a through hole 31a formed in the center, and a step portion 31b is formed on the outer periphery of a lower end portion. The bottom plate 32 has a through hole 32 at the center.
a is formed in a disk shape having an outer diameter substantially the same as the outer diameter of the core member 31. A cylindrical spring guide 3 is disposed on the upper surface of the core member 31 by inserting a bolt 33 from the bottom plate side through the through hole 32a of the bottom plate 32 and the through hole 31a of the core member 31.
4 and assembled between the female screws formed. An O-ring 35 for sliding sealing is mounted in a circumferential groove formed between the step 31b on the lower end surface of the core member 31 and the upper surface of the bottom plate 32, and is disposed in the sub cylinder 20. Further, on the upper surface of the weight piston 21, an elastic member 36 for buffering an impact and reducing noise in the event of a collision with the inner wall surface of the cylinder cap 19 is disposed.

Next, the operation of the nailing machine according to the above embodiment will be described. Normally, as shown in FIG. 1, the projection 15 ′ of the drive piston 15 is
3 'is held at the top dead center position in the drive cylinder 14, and the weight piston 21 is
Is located at the bottom dead center position in contact with the upper end surface of the piston stop 23. In the drive cylinder 14 between the drive piston 15 and the weight piston 21, the main valve 25 is located at the bottom dead center position by the action of the compressed air supplied into the control chamber 25 'through the trigger valve 29. And is connected to the exhaust port 26 to be at atmospheric pressure.

When the trigger valve 29 is operated by pressing the nailing machine against the material to be driven and operating the safety device 28 and manually operating the trigger lever 27, the main valve 2
5 is released to the atmosphere from the trigger valve 25 via the air passage 30 by the compressed air pressure in the main chamber 13 in which the lower end of the main valve 25 acts on the lower end thereof. Move to. When the main valve 25 is moved upward, the air supply port 24 becomes the exhaust port 2.
6 and connected to the main chamber 13 at the same time as the compressed air in the main chamber 13 is introduced into the drive cylinder 14. The compressed air introduced into the drive cylinder from the air supply port 24 acts on the upper end surface of the drive piston 15 to drive the drive piston 15 downward. Further, the compressed air is introduced into the sub-cylinder 20 via an opening opened at the center of the piston stop 23, and the weight piston 2
1 to drive the weight piston 21 upward.

When the drive piston 15 is driven downward in the drive cylinder 14, a driver 16 integrated with the drive piston 15 drives out the nail previously supplied into the nose member 17 from the nose member 17, and It is driven into the material to be driven arranged at the lower end. On the other hand, weight piston 2
1 is driven upward against the compression spring 22. The reaction force generated when the drive piston 15 is driven is the drive piston 1
The upward movement of the weight piston 21 having a diameter larger than 5 is completely absorbed and does not generate any reaction force for moving the housing 11 upward. A part of the reaction force due to the upward drive of the weight piston 21 having a diameter larger than that of the drive piston 15 is offset by the reaction force of the drive piston 15. The reaction force is generated downward by the diameter difference between the cylinder 14 and the sub-cylinder 20, and the reaction force is transmitted to the housing 11 via the drive cylinder 14 to move the housing 11 downward.

As the weight piston 21 moves upward, an upward force acts on the cylinder cap 19, that is, the housing 11, via a compression spring 22 interposed between the weight piston 21 and the cylinder cap 19. If the above-described diameter difference is set so that the magnitude of the force via the compression spring 22 and the magnitude of the downward driving force generated by the diameter difference become equal, the upward movement due to the recoil of the housing 11 is substantially prevented. Completely gone. It is also possible to set the diameter difference larger so that the downward reaction force generated by the diameter difference becomes larger so that a downward operating force is positively generated in the housing 11.

When the operation of the trigger lever 29 and the safety mechanism 28 is released after the nail driving is completed and the trigger valve 29 returns to the initial state, compressed air is supplied again into the control chamber 25 'of the main valve 25, and The valve 25 returns to the lower position. By the return of the main valve 25, the interiors of the drive cylinder 14 and the sub cylinder 20 are connected to the atmosphere via the exhaust port 26, and the compressed air in both cylinders is discharged. The driving piston 15 receives compressed air stored in a return chamber 14 ′ formed around the driving cylinder 14, receives the compressed air on its lower surface, and ascends and returns to the top dead center. Stopped by being locked by '.
On the other hand, the weight piston 21 returns to the bottom dead center in contact with the upper surface of the piston stop 23 by the action of the compression spring 22.

Next, another embodiment of the present invention shown in FIGS. 3 and 4 will be described. As shown in detail in FIG. 4, the weight piston 40 is composed of a piston main body 41, 42 which is formed of a metal material such as iron or aluminum in two upper and lower parts.
And a core member 43 made of a metal having a high specific gravity such as lead or tungsten, which is accommodated in a hollow portion formed inside the piston bodies 41 and 42. The piston main body 41 forming the upper part of the weight piston 21 has a disc-shaped lid 41a having an opening 41b formed at the center thereof and a lid 41.
A cylindrical portion 41 extending downward from the periphery of the peripheral wall 41c and the central opening 41b formed downward from the outer peripheral edge of a.
d, and the piston main body 42 forming the lower part of the weight piston 21 is similarly formed with a bottom 42a, an opening 42b,
It is composed of a peripheral wall 42c rising upward and a cylindrical portion 42d extending upward. Further, a peripheral groove 44 for accommodating an O-ring 45 for sealingly sliding with the inner surface of the sub-cylinder 20 is formed on the outer peripheral surface of the peripheral walls 41c, 42c of the piston main bodies 41, 42.

The core member 43 is formed in a substantially donut shape having a through hole 43a formed in the center so as to be accommodated between the peripheral walls 41c, 42c of the piston bodies 41, 42 and the cylindrical portions 41d, 42d. The upper and lower piston main bodies 41 and 42 are fixed by bolts 46 inserted through the openings 41b from the piston main body 41 side which accommodates the core member 43 between the upper and lower piston main bodies 41 and 42, and the circumferential groove 44 After attaching the O-ring 45 to the cylinder cap 19
Are accommodated and arranged in the sub cylinder 20. A cylindrical spring guide 47 for guiding the compression spring 22 by the bolt 46 is integrally fixed to the upper surface of the piston main body 41. Further, on the upper surface of the weight piston 40, an elastic member 48 for buffering an impact and reducing noise at the time of collision with the inner wall surface of the cylinder cap 19 is arranged.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing an embodiment in which the impact mechanism of the present invention is used in a nailing machine.

FIG. 2 is an exploded perspective view showing a weight piston structure of the impact mechanism of FIG.

FIG. 3 is a longitudinal sectional side view showing another embodiment of the present invention.

FIG. 4 is a perspective view showing a weight piston structure of the impact mechanism of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Nailer 11 Housing 12 Grip part 13 Main chamber 14 Drive cylinder 15 Drive piston 16 Driver 17 Nose part 18 Bumper 19 Cylinder cap 20 Sub cylinder 21 Weight piston 22 Compression spring 23 Piston stop 24 Air supply port 25 Main valve 25 'control Chamber 26 Exhaust port 27 Trigger lever 28 Safety mechanism 29 Trigger valve 30 Air passage 31 Core member 32 Piston substrate 33 Bolt 34 Spring guide 35 O-ring 36 Elastic member 40 Weight piston 41, 42 Piston main body 41a, 42a Lid 41b, 42b Open 41c , 42c Peripheral wall 41d, 42d Cylindrical part 43 Core member 44 Peripheral groove 45 O-ring 46 Bolt 47 Spring guide 48 Elastic member

Claims (3)

(57) [Scope of request for utility model registration] 1. A drive cylinder fixedly disposed in a housing of a tool, and a drive piston slidably housed in the drive cylinder, and compressed air is introduced into an upper surface of the drive piston in the drive cylinder. An impact mechanism for driving the driving piston, comprising a downward effective surface facing the upper chamber of the driving piston of the driving cylinder, and slidably disposed in the operating axis direction of the driving piston. A weight piston structure, wherein at least a part of the weight piston is made of a high specific gravity metal. 2. The weight according to claim 1, wherein a core material made of a metal having a high specific gravity is sealed in a piston main body in which the weight piston is made of iron, aluminum or the like in a hollow shape. Piston structure. 3. The weight piston structure according to claim 1, wherein the weight piston is divided into a plurality in the axial direction, and at least one of the weight pistons is made of a high specific gravity metal.