JPH0666968U - Fixing tool striking tool - Google Patents

Abstract

(57) [Summary] [Purpose] A striking tool that has sufficient shock absorption even with a small bumper. [Structure] When pressurized air is supplied from the upper part of the cylinder 4 of the fastener impact tool 1, the piston 6 rapidly descends, and the impact member 5 drives the fastener at the nose 10 into the object.
When the air in the upper part of the cylinder is exhausted to the atmosphere, the pressurized air in the return air chamber 11 acts on the lower surface of the piston 6 and the piston returns to the upper part of the cylinder. A bumper 16 is provided at the lower end side of the cylinder to absorb the shock caused by the sudden lowering of the piston, and the striking member 5 has a cross-sectional area of the portion from the tip end side thereof to the vicinity of the root connected to the piston. The base portion 23 of the striking member 5 adjacent to the piston 6 is formed to be smaller than the area of the striking member passage 10a of the nose so that compressed air can be discharged from the nose 10 while being supplied to the return air chamber 11. A large cross-sectional area is formed to seal the passage and prevent exhaust to the nose, and the impact on the bumper 16 at the bottom dead center of the piston 6 is reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastener hitting tool such as a nail driving machine, and more particularly to a mechanism for protecting a bumper that absorbs an impact caused by a rapid lowering of a piston.

[0002]

[Prior art]

 Pressurized air is supplied to the housing, a cylinder is provided inside the housing, and a piston with a rod-shaped striking member is reciprocally mounted inside the cylinder. When supplied, the piston rapidly descends and drives the fastener with the striking member in the nose into the object.At this time, while exhausting slightly from the striking member passage of the nose to the nose side, it is between the cylinder and the housing. When pressurized air is supplied to the formed return air chamber, and then the air in the upper part of the cylinder is exhausted to the atmosphere, the pressurized air in the return air chamber acts on the lower surface of the piston and the piston returns to the upper part of the cylinder. The impact tool that absorbs the shock caused by the sudden lowering of the piston is provided on the bottom surface of the cylinder. It is has been, has been widely used in the construction site or the like.

[0003]

[Problems to be solved by the device]

 In a conventional fastener impact tool, if a bumper with a high strength and hardness is used, the durability will increase, but the shock absorption will be low, and the shock will be transmitted to the entire tool, and the shock will be transmitted to the hands of workers, etc. Moreover, the parts of the tool may be damaged. On the other hand, if a soft bumper is used, the shock absorption is improved, but the durability of the bumper is reduced, and if the deformation force is large, the bumper may be plastically deformed or may generate heat, resulting in damage. In addition, excessive bending of the bumper may cause the piston to descend too much in the cylinder, and the O-ring for sealing the piston may come off from the cylinder. For this reason, a slightly harder rubber material is used for the bumper, which is made larger to increase the impact absorption. In this way, because the bumper is large, the tooling becomes large, which is a bottleneck for downsizing.

Therefore, an object of the present invention is to provide a fastener hitting tool having a sufficient shock absorbing power even if the bumper is small.

[0005]

[Means for Solving the Problems]

 In order to achieve such an object, according to the present invention, pressurized air is supplied to the housing, a cylinder is provided inside the housing, and a piston having a rod-shaped striking member mounted therein reciprocates. When it is movably arranged and pressurized air is supplied from the upper part of the cylinder, the piston suddenly descends and the striking member passes through the striking member passage of the nose and drives the fastener in the nose to the object, then When the air in the upper part of the cylinder is exhausted to the atmosphere, the pressurized air in the return air chamber acts on the lower surface of the piston to return the piston to the upper part of the cylinder. Is a fastener striking tool in which a bumper that absorbs is attached to the lower end side of the cylinder, wherein the rod-shaped striking member is located near the base connected to the piston from its tip side. The cross-sectional area of the portion up to is formed to be smaller than the area of the striking member passage of the nose so that the pressurized air on the lower surface side of the piston can be discharged from the nose while supplying the pressurized air to the return air chamber. The fastener striking tool is characterized in that the root portion of the member has a large cross-sectional area so as to seal the striking member passage of the nose and prevent exhaust to the nose.

[0006]

【Example】

 An embodiment of a fastener striking tool according to the present invention will be described below with reference to the drawings. A fastener hitting tool 1 for hitting a fastener such as a nail has a housing 3 in which a handle 2 is integrally formed, and pressurized air is supplied to the housing 3 from the handle 2 side. . A cylinder 4 is provided inside the housing 3, and a piston 6 to which a rod-shaped striking member 5 is attached is reciprocally arranged inside the cylinder 4. A main valve 7 is provided on the upper end of the cylinder 4, and this main valve seals the upper end of the cylinder 4 and does not supply pressurized air into the cylinder in the housing 3; The seal at the upper end of is removed to take a striking position (not shown) for supplying pressurized air from the housing 3. The striking position of the main valve 7 is the position where the main valve 7 has risen in the direction of the arrow 8. At this striking position, as shown by the arrow 9, the compressed air flows from the gap between the main valve 7 and the upper end of the cylinder 4. Is supplied to the upper part of the piston 6, and the piston 6 is strongly and rapidly pushed downward.

By this pushing down, the hitting member 5 hits the fixing tool on the nose 10 and hits the object such as a plate. During this driving, most of the compressed air on the lower surface side of the piston 6 that descends by shock is supplied to the return air chamber 11 formed between the lower portion of the cylinder 4 and the housing 3 on the outer circumference of the cylinder 4. Then, the nose 10 is also exhausted to some extent to keep the striking force of the striking member 5 constant. While the descending piston 6 is in the upper part of the cylinder, the air below the piston 6 is stored in the return air chamber 11 mainly through the hole 13 on the lower end side of the cylinder 4, and the piston 6 passes through the pilot hole 12. Then, not only the air below the piston is supplied through the hole 13 on the lower end side, but also the pressurized air in the cylinder chamber above the piston is newly supplied through the pilot hole 12. Since the pilot hole 12 is provided with an O-ring 14 as a check valve, it does not flow backward from the pilot hole 12 to the cylinder side, and a sufficient amount of pressurized air is stored in the return air chamber 11. Therefore, when the main valve 7 returns to the rest position shown in the figure, the air in the cylinder chamber above the piston is exhausted to the atmosphere, and the pressurized air in the return air chamber 11 passes through the hole 13 on the lower end side into the cylinder chamber below the piston. The pressurized air flows in and acts on the lower surface of the piston 6, and the piston 6 returns to the upper portion of the cylinder 4. A bumper 16 is provided at the lower end side of the cylinder to absorb the shock caused by the sudden lowering of the piston 6. Further, the piston 6 is provided with an O-ring 17 that forms a seal with the cylinder 4.

The main valve 7 is controlled by a trigger device 18 provided at the base of the handle 2. That is, when the trigger pin 19 is in the rest position without being pushed, the pressurized air that has passed through the trigger device 18 enters the main valve chamber 21 through the pipe 20 shown by the broken line, and the main valve 7 is pushed downward. It is in the position shown. No pressurized air is supplied to the cylinder 4, and no pressurized air is sent to the upper surface of the piston 6. Next, when the trigger pin 19 is pushed upward, the air in the main valve chamber 21 is exhausted to the atmosphere through the trigger device 18, and since the force for pushing down the main valve 7 is lost, the main valve 7 is pushed up and the arrow 8 indicates. As shown by the arrow 9, pressurized air is supplied to the upper part of the piston 6, and the piston 6 is strongly pushed downward so that the striking member 5 drives the nose fastener into the target object. . When the trigger pin 19 is released, it returns to the original position and the main valve 7 returns to the rest position shown. That is, the pressurized air is no longer supplied to the upper surface side of the piston 6 that has been pushed down, and the action of the pressurized air from the return chamber 11 causes the piston 6 to move inside the cylinder 4 from its bottom dead center. To rise.

The piston 6 rapidly descends to the lower end side of the cylinder 4 in order to drive the fastener into the object. The bumper 16 is essential for stopping the piston 6. The bumper 16 is arranged on the lower end side of the cylinder 4, and is formed in a donut shape having a hole through which the striking member 5 passes, and shocks due to a rapid downward movement of the piston 6 are distributed over the entire circumference thereof. Absorb across. If this bumper is made of hard and strong material, its durability will increase, but its shock absorption will be low, and the shock will be transmitted to the entire tool, and it will also be transmitted to the hands of workers, and the parts of the tool It will be damaged. On the other hand, when a soft bumper is used, the shock absorption is improved, but the durability of the bumper is reduced, and the deformation becomes large, and the bumper may be plastically deformed or may be heated and damaged. Furthermore, the excessive bending of the bumper causes the piston 6 to move down and down in the cylinder 4 too much, causing the sealing O-ring 17 of the piston 6 to come off the cylinder 4, which requires disassembly and repair.

In the present invention, the impact of the piston 6 on the bumper 16 is mitigated. That is, as also shown in FIG. 2, in the rod-shaped striking member 5, the portion from the tip side to the vicinity of the root connected to the piston, as in a normal case, sends the pressurized air on the lower surface side of the piston to the return air chamber. The inner diameter of the striking member passage 10a is smaller than the inner diameter of the striking member passage 10a so that the air can be discharged from the nose 10 while being supplied to the nozzle 11. However, the base portion 23 of the striking member adjacent to the piston is formed to have a larger diameter than the other portions, and seals the inlet portion of the striking member passage 10a so that the nose 10 is not substantially exhausted. That is, an O-ring 25 is provided at the entrance of the striking member passage 10a, and the large-diameter root portion 23 cooperates with the O-ring 25 to leak the pressurized air on the lower surface of the piston to the nose 10 side. It is sealed to prevent it.

The operation of the piston 6 when the striking member 5 strikes the fastener will be described. In FIG. 1, when the trigger pin 19 is pushed upward, the main valve 7 is pushed up to the striking position as shown by the arrow 8, and pressurized air is supplied to the upper part of the piston 6 as shown by the arrow 9. Is strongly and rapidly pushed downward, the tip of the striking member 5 projects into the nose 10, and the fastener in the nose 10 is driven into the object. FIG. 2 shows a state in which the piston 6 is pushed down to the bottom dead center. As is clear from this figure, the large-diameter root portion 23 of the striking member 5 seals the striking member passage 10a and prevents the pressurized air in the lower surface side of the piston 6 and the return air chamber 11 from escaping. ing. For this reason, the air on the lower surface side of the piston 6 is largely pressed by the strong and abrupt depression of the piston 6, and acts as a force to push the piston 6 upward. Due to the action of the pressurized air, the impact force of the piston 6 on the bumper 16 is greatly attenuated. Due to the reduction in the impact force and the impact absorption force of the bumper 16, the impact absorption performance is greatly improved. Also, since the impact force on the bumper 16 is small, a small bumper can be used, and the impact absorption can be further improved by using a soft bumper. Further, the noise caused by the impact is greatly reduced, and the vibration of the tool is also significantly reduced. The seal between the base portion 23 of the striking member 5 and the striking member passage 10a is performed by pushing up the piston 6 that the air on the lower surface side of the piston 6 is shocked and descends to or near the bottom dead center. It does not have to be a completely airtight seal as long as it does not exhaust so much as to reduce the impact. Further, even if the impact force is reduced in this way, the impact force of the piston 6 is only reduced at or near the bottom dead center, so that the fastener is sufficiently driven into the target object and there is no hindrance to the impact. It was When the trigger pin 19 is released after the fastener is driven, the pressurized air on the upper surface side of the piston 6 is discharged to the atmosphere and the supply of new pressurized air is stopped, and the action of the pressurized air from the return chamber 11 is exerted. Thus, the piston 6 rises in the cylinder 4 from its bottom dead center.

[0012]

[Effect of device]

 According to the striking tool of the present invention, the rod-shaped striking member has a cross-sectional area from the tip end side to the root portion connected to the piston, and supplies pressurized air on the piston lower surface side to the return air chamber. In addition, the area of the striking member passage of the nose is formed to be smaller than the area of the striking member passage of the nose, and the base portion of the striking member adjacent to the piston seals the striking member passage of the nose to prevent exhaust to the nose. Since the cross-sectional area is large, the air on the bottom surface of the piston is greatly pressurized near the bottom dead center of the piston and pushes the piston upward, and the impact force with which the piston strikes the bumper is Greatly attenuates. Therefore, the impact absorption performance is greatly improved by the reduction of the impact force and the impact absorption force of the bumper, which allows the use of a small bumper and further the impact absorption performance by using a soft bumper. . That is, even if the bumper is small, a sufficient shock absorbing force can be maintained for a long time, and the entire tool can be made small. Since the impact force on the bumper was greatly attenuated, the noise inside the tool was greatly reduced, and the vibration due to the impact on the hand was also reduced, making the work of driving the fastener very easy.

[Brief description of drawings]

FIG. 1 is a cutaway front view of a main part of a fastener striking tool according to the present invention.

FIG. 2 is an enlarged view of a bumper portion of the tool in a striking position.

[Explanation of symbols]

 1 Fixing Tool Hitting Tool 2 Handle 3 Housing 4 Cylinder 5 Hitting Member 6 Piston 7 Main Valve 10 Nose 10a Hitting Member Passage 11 Return Air Chamber 12 Pilot Hole 14 Check Valve O-Ring 16 Bumper 18 Trigger Device 19 Trigger Pin 21 Main Valve Chamber 23 Base part of striking member 25 O-ring

Claims (1)

[Scope of utility model registration request] 1. A pressurized air is supplied to a housing, a cylinder is provided inside the housing, and a piston having a rod-shaped striking member mounted therein is reciprocally arranged inside the cylinder. When pressurized air is supplied, the piston rapidly descends and the striking member drives the fastener in the nose through the striking member passage of the nose into the target object, then the air above the cylinder exhausts to the atmosphere. Then, the pressurized air in the return air chamber acts on the lower surface of the piston so that the piston returns to the upper part of the cylinder, and the bumper that absorbs the shock due to the sudden lowering of the piston moves to the lower end side of the cylinder. In the provided fastener striking tool, the rod-shaped striking member is such that the cross-sectional area of the portion from the tip end side to the vicinity of the root connected to the piston is the piston bottom surface. Is formed smaller than the area of the striking member passage of the nose to the extent that it can be exhausted from the nose while supplying pressurized air on the side to the return air chamber,
The fastener striking tool, wherein a base portion of the striking member adjacent to the piston has a large cross-sectional area so as to seal the striking member passage of the nose and prevent exhaust to the nose.