JP3531350B2 - Compressed air screw tightening machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressed air screw tightening machine for tightening screws by using compressed air, and is intended to surely perform screw tightening and to reduce recoil.

[0002]

2. Description of the Related Art For example, a compressed air screw tightener for tightening a screw for attaching a relatively soft gypsum board or the like to a material to be fastened to a mounting material such as relatively hard wood is disclosed in JP-A-5-26.
Proposed in No. 1676. This compressed air screw tightener is supported so as to be movable up and down in an air motor that is rotated by compressed air, and is mounted so as to rotate together with the air motor. A moving member having a drive bit is provided at the lower end, and the moving member is moved by compressed air. The screw is tightened by lowering it while rotating it.

Therefore, since only the lightweight moving member is lowered, there is an advantage that the impact can be reduced and the main body can be downsized, and as a result, the operability can be improved. However, since the moving member is made to descend by compressed air, it is necessary to consider the pressure fluctuation of the compressed air, and when the pressure becomes large, the striking force becomes larger than that of screwing in the screw, and it is driven. As a result, there is a problem that the fastening force of the screw becomes small.

When the screw tip hits the mounting material,
There has been a problem that the moving member suddenly stops due to the resistance of the mounting material, and as a reaction force thereof, a reaction occurs in which the main body floats up, resulting in insufficient tightening of the screw. In order to reduce the recoil, a cylindrical movable piston having an upper end closed and an lower end opened is supported by a moving member so as to be vertically movable, and a spring is provided between the upper end of the movable piston and the moving member flange, and compressed air is used. A compressed air screw tightener that lowers the recoil by lowering the movable piston and the moving member, and when the tip of the screw hits the mounting material and the moving member suddenly stops, the movable piston is lowered while compressing the spring. It was proposed in Japanese Patent Application No. 5-318273 (JP-A-7-171770).

[0005]

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention
The pneumatic screw tightener is designed to prevent the screw tip from hitting the mounting material.
The recoil can now be reduced. However, the mobile fixie
During the tightening of the screw to the mounting material,
( Occupies most of the time during screwdriver operation )
Ends on the moving member and movable piston via the spring.
Initial compressed air pressure works, and as a reaction force, upward pressure is applied to the main body.
Since compressed air is working, the main body floats up due to compressed air.
The reduction of the recoil that occurs in the rising direction was insufficient. others
Therefore, the main body rises and the drive bit is
The drive bit that had been mated with the screw
It may come off the screw head groove, and the screw may not be tightened sufficiently.
There was a problem that As mentioned above, the pressure of compressed air
When the force increases, the force to hit rather than screw in the screw
Has become larger and has become to be driven, and the screw
There was a problem that the fastening force becomes small.

An object of the present invention is to eliminate the above-mentioned problems of the prior art, to ensure that screw tightening can be performed reliably and completely regardless of pressure fluctuations of compressed air, and to allow recoil to be reliably reduced during screw tightening. It is to be.

[0007]

In order to achieve the above purpose, the moving member
After the movable piston hits the stopper, a spring is provided between the upper end of the movable piston having a diameter smaller than that of the movable member and the flange of the movable member , and a stopper for preventing the movable piston from descending more than a predetermined amount is provided. Is
The restoring force of the spring lowers the moving member and tightens the screw.
It is achieved by doing . Further, by allowing the movable piston to abut on the stopper before the tip of the screw abuts on the tightened material or at the latest, the mounting material, the reaction can be more reliably reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing one embodiment. The body 1 has a pressure accumulating chamber 11 inside.
Etc. and a housing 30 containing an air motor 13, which will be described later, a moving member 7 and the like, a magazine for housing the screws 10 held by a band 17, a housing 30
It is composed of a nose and the like that are mounted on the lower end of the. The inner wall of the rotor 16 of the air motor 13 provided at the intermediate portion in the up-down direction of the housing 30 constitutes a cylinder 2 of the movable piston 3 described later. An air inlet 20 is provided above the cylinder 2, and a head valve 24 is further provided above the air inlet 20. The head valve 24 is always pushed downward by the compressed air in the head valve upper chamber 6 as in the case of a normal nailing machine, so that the air inlet passage 20 and the pressure accumulating chamber 11 are shut off from each other. As is well known, when the trigger valve is operated by the operation of the trigger 5 and the compressed air in the head valve upper chamber 6 is discharged, the head valve 24 is pushed up by the compressed air to remove the compressed air in the pressure accumulating chamber 11. It is made to flow into the intake passage 20.

A drive bit 9 is attached via a clutch 15 to the lower end of the spline shaft 8 rotated by the rotor 16 via a ball spline 14 provided below the rotor 16, and on the upper end of the spline shaft 8. Is equipped with a large-diameter valve seal portion 21, and the spline shaft 8, drive bit 9 and valve seal portion 21 rotate and move up and down as a unit.
Make up. The clutch 15 disconnects the connection between the spline shaft 8 and the drive bit 9 when a predetermined tightening torque is reached . Further, in the valve seal portion 21, the moving member 7 descends by a predetermined amount (when the valve seal portion 21 is on the cylinder 2).
When the screw tightening is completed, the valve
The outer peripheral seal portion of the seal portion 21 is fitted to a portion having a slightly smaller diameter below the air inlet passage 20 to shut off the air passage between the air inlet passage 20 and the air motor 13, so that compressed air is wasted. Is to prevent. In addition, as shown in FIG.
Until the bushing part 21 hits the upper end surface of the cylinder 2.
Is greater than the outer diameter of the outer peripheral seal of the valve seal 21.
The diameter of the passage 20 is large and the outer peripheral seal portion of the valve seal portion 21 is
And there is a gap between the cylindrical wall around the intake passage 20 and
ing.

The movable piston 3, which is supported above the spline shaft 8 so as to be movable up and down, is formed in a cylindrical shape with its upper end closed and its lower end opened. A moving piston ring is provided.
The seal diameter of the movable piston 3 is the axis of the moving member 7.
Is larger than the shaft diameter of the spline shaft 8. The movable piston 3 is formed so that its mass is smaller than that of the moving member 7. A spring 4 is provided between the inner wall of the upper end of the movable piston 3 and the flange 22 of the spline shaft 8. The compression force of the spring 4 is the same as in the above-mentioned Japanese Patent Laid-Open No. 7-1.
The moving force is smaller than the compression force of the 71770 spring.
The descending speed of the stone 3 is higher than the descending speed of the moving member 7.
At this time, the spring 4 is compressed by the movable piston 3.
Further, the stroke of the movable piston 3 is set so as to be equal to or larger than the screwing amount by which the screw 10 is screwed into the mounting member 32. Cylinder 2 above the ball spline 14
A stopper 40 that protrudes inward is provided at the inner end of the inner wall to prevent the movable piston 3 from descending by a predetermined amount or more. In addition,
Reference numeral 12 denotes a push lever whose lower end is held so as to be vertically movable around the nose and whose upper end extends to the vicinity of the trigger 5. The push lever 12 moves upward when the lower end of the nose is pressed against the tightened material 31, and operates the trigger 5. The trigger valve is operated by the.

When the nose of the main body 1 is pressed against the material 31 to be tightened, the push lever 12 rises, and when the trigger 5 is operated, the trigger valve operates as described above and the compressed air in the head valve upper chamber 6 is discharged. As a result, the head valve 24 rises, and the compressed air in the pressure accumulating chamber 11 is rapidly supplied into the intake passage 20. In the first state immediately after the inflow of compressed air
The air motor 13 is driven to rotate by the compressed air supplied into the intake passage 20, and the inflow of the compressed air is very small.
Since the moving member 7 has a large mass because it is instantaneous, it has a large inertia.
It does not descend and has a small mass, that is, a small inertia
The movable piston 3 resists the biasing force of the spring 4 first.
The moving spring 4 is moved down while being compressed . Movable fixie
The pressure receiving area of the moving member 7 is, as is clear from FIG.
Is larger than the pressure receiving area of the
Since the mass of the moving member 7 is smaller than that of the moving member 7, the movable piston 3 is lowered.
The speed becomes higher than the descending speed of the moving member 7. This conclusion
As a result, the movable piston 3 moves downward while compressing the spring 4.
It descends, hits the stopper 40, and stops. After this
In the second state, the restoring force of the spring 4 acts on the spline shaft 8 via the flange 22, and the moving member 7 disengages the screw 10 from the band 17 so that the tip of the screw 10 is fastened to the tightened material 3
Press on 1. The moving member 7 descends to the position shown in FIG.
Due to the resistance when the screw 10 penetrates the material 31 to be tightened and enters the mounting material 32, the moving member 7 rapidly decreases in descending speed. In this state, the compressed air acts on the movable piston 3, but the movable piston 3 hits the stopper 40 as shown in FIG. And there is no recoil. This state continues until the screw tightening in FIG. 4 is completed.

After the movable piston 3 hits the stopper 40, the moving member 7 is lowered almost by the restoring force of the spring 4, so that the screw tightening can be performed without being affected by the pressure fluctuation of the compressed air. Since the moving member 7 is lowered by the spring 4 with a substantially constant force, the engagement holding force between the drive bit 9 and the head groove of the screw 10 is kept substantially constant. Further, since the drive bit 9 is rotating, the screw 10 is lowered and screwed while rotating along the lead. Since the mesh holding force is the minimum mesh holding force corresponding to the advance of the screw, the urging force of the spring 4 can be reduced and the pressing force of the movable piston 3 by the compressed air can be reduced. When the moving member 7 is lowered by the restoring force of the spring 4, the moving member 7 has a difference in area between the upper and lower surfaces of the valve seal portion 21, in the case of the present embodiment, the compressed air by the area of the spline shaft 8. Force is applied, but this value is small and has almost no effect.
After tightening the screw, operate the trigger 5 to operate the trigger valve.
Then, the head valve upper chamber 6 is stored like a normal nailer.
Compressed air flows in from the pressure chamber 11 to generate compressed air and sprinkles.
The head valve 24 is lowered by
The lower end surface is contact-sealed, and the upper end surface side is from the housing 30.
Separated and opened. Valve seal from this opening
The pressure of the space above the part where the part 21 hits and seals
Compressed air is exhausted to the atmospheric pressure and the clutch 15
And a moving member 7 by a spring provided between the bottom of the main body
And the movable piston 3 returns to the initial top dead center position, and as shown in FIG.
Become

In the above embodiment, the valve seal portion 21 is integrally fixed to the moving member 7 at the end of screw tightening.
Since the air passage between the air intake passage 20 and the air motor 13 is blocked by the above so as to prevent wasted consumption of compressed air, an initial period from the seal portion on the housing 30 side to the valve seal portion 21 is reduced. It is necessary to set the length to the length of the entire stroke of the moving member 7, and as a result, the total length of the main body 1 becomes long and the main body 1 becomes large.

FIG. 5 shows another embodiment of the present invention invented in order to solve such a problem. The same parts as those in the above embodiment are designated by the same reference numerals. A stopper 50 corresponds to the stopper 40, and is provided below the main body 1 facing the lower end of the movable piston 3. The moving seal member 5 urged upward by the spring 52
A sealing material is attached to the bottom of the upper flange of the No. 1 and the sealing material comes into contact with the fixed wall 53 of the main body 1 to shut off the air passage between the air motor 13 and the intake passage 20. The moving seal member 51 is moved down as the moving member 7 is lowered by pushing down the lower end flange of the moving seal member 51 located below the fixed wall 53 by the large diameter portion provided at the upper end of the moving member 7. Movable piston 3
Is vertically movably supported by a downward protruding portion of the air motor 13 protruding downward from the rotor 16, and a spring 4 is provided between the upper portion of the movable piston 3 and the lower end flange of the moving member 7. The compressed air in the intake passage 20 is
6 is supplied to the upper surface of the movable piston 3 via a groove 60 shown in FIG. A plurality of holes (not shown) are provided in the upper flange portion of the moving seal member 51 to supply compressed air into the moving seal member 51.

According to this embodiment, as in the above embodiment, when the head valve 24 is raised, the air motor 13 is rotationally driven, and the inflow of compressed air is very instantaneous, so that the moving member 7 having a large mass has inertia. A movable pie that is large and hardly descends and has a small mass, that is, a small inertia
The ton 3 moves first and the movable piston 3 descends. As is apparent from FIG. 3, the pressure receiving area of the movable piston 3 is larger than the pressure receiving area of the moving member 7, and the mass of the movable piston 3 is smaller than the mass of the moving member 7. It is greater than the descending speed of. As a result, the movable piston 3 descends while compressing the spring 4, hits the stopper 50, and stops. After this,
The restoring force of the spring 4 acts on the moving member 7 via the lower end flange, the moving member 7 descends, the drive bit 9 disengages the screw 10 from the band 17, and the tip of the screw 10 is pressed against the tightened material 31. . The moving member 7 descends, and the screw 1
Due to the resistance when 0 penetrates the material 31 to be fastened and enters the mounting material 32, the descending speed of the moving member 7 rapidly decreases.
In this state, the compressed air acts on the movable piston 3, but since the movable piston 3 abuts on the stopper 50, the compressed air pushes down the main body 1 and the main body 1.
The forces that push up are offset, and there is no recoil. When the moving member 7 descends by a predetermined amount, the large-diameter upper portion moves to the moving seal member 51.
Of the movable seal member 51 is engaged with the lower end flange of the movable seal member 51, and the seal material of the movable seal member 51 abuts the fixed wall 53 at the end of screwing to shut off the air passage between the air intake passage 20 and the air motor 13. Useless compressed air is not supplied to the air motor 13.

According to this embodiment, the lower end flange of the moving seal member 51 that is engaged with the large diameter portion of the upper end of the moving member 7 and is pushed down is located below the fixed wall 53, and the screw tightening is completed by the moving seal member 51. Since the supply of compressed air to the air motor 13 is stopped at times, the length of the moving member 7 and the total length of the main body 1 can be shortened, and as a result, the screw tightener can be reduced in size and weight. Therefore, it is possible to obtain the effect of improving the operability.

In the above embodiment, the material to be tightened is the gypsum board which is relatively soft, but it may be wood.
In this case, the need Ru screw tip is so movable piston 3 before the strike the timber is a material clamp object abuts against the stopper 40.

[0018]

As described above, according to the present invention, since the moving member, that is, the drive bit is lowered by the restoring force of the elastic body to perform the screw tightening, the pressure fluctuation of the compressed air is not affected. The screw can be securely and completely tightened, and the tightening force of the screw can be prevented from decreasing. When the tip of the screw hits the material to be tightened or the mounting material, the movable piston hits the stopper so that the reaction force of the compressed air does not act on the body, so it is possible to reduce the recoil. It is possible to prevent the tightening failure due to.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a compressed air screw tightener of the present invention.

FIG. 2 is a cross-sectional view showing the operating state of FIG.

FIG. 3 is a partially enlarged cross-sectional view of FIG. 2 showing a main part of the present invention.

FIG. 4 is a cross-sectional view showing a state after the screw tightening of FIG. 1 is completed.

FIG. 5 is a sectional view of an essential part showing another embodiment of the present invention.

FIG. 6 is an A- of FIG. 5 showing an example of a rotor of an air motor.
A line sectional view.

[Explanation of symbols]

1 is a main body, 2 is a cylinder, 3 is a movable piston, 4, 52
Is a spring, 7 is a moving member, 8 is a spline shaft, 9 is a drive bit, 13 is an air motor, 16 is a rotor, 2
2 is a flange, 40 and 50 are stoppers, 51 is a moving seal member, and 53 is a fixed wall.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-171770 (JP, A) JP-A-64-45579 (JP, A) JP-A-58-10465 (JP, A) JP-B 3- 46270 (JP, B2) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B25B 21/00 B25B 21/00 530 B25D 16/00

Claims (4)

(57) [Claims] 1. An air motor, which is rotatably supported in a main body having a trigger valve and is rotated by compressed air introduced by the operation of the trigger valve, and an inside of the air motor.
And a moving member having a drive bit at its lower end, the moving member being supported so as to be movable up and down, and having a drive bit at its lower end. The compressed air screw tightening machine lowers the moving member while rotating it by compressed air and tightens the screw. The moving member so as to slide in the air motor in the axial direction.
Supported, mass less than mass of moving member, diameter moving
A movable piston that is larger than the diameter of the member and that the moving member penetrates.
Is interposed between the movable piston and the flange of the moving member , and the lowering speed of the moving piston is lower than the lowering speed of the moving member.
Movable to block a spring <br/> which is compressed by the movable piston is greater, the predetermined or more descent of the movable piston
The operation of the trigger valve is provided with a stopper provided on the main body other than the moving member located on the movement path of the piston.
A movable piston lowered by compressed air introduced by
The lowering speed of the stone is faster than the lowering speed of the moving member.
In the state, the movable piston resists the biasing force of the spring.
The spring moves downward while compressing the spring, and after the second state in which the movable piston is blocked by the stopper , the spring is sprinkled.
Screwing so as to lower the movable member by the restoring force of the grayed
A compressed air screw tightener characterized by performing . 2. The compressed air screw tightener according to claim 1, wherein the movable piston abuts on the stopper before the screw tip abuts on the material to be tightened. 3. The air motor, wherein the stopper is provided below the movable piston.
Compressed air screw tightener as described. 4. The compressed air screw tightener according to claim 1, wherein the stopper is provided on a screw tightener main body located below the movable piston.