JPH09300238A - Driver blade for a driving machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce reaction at driving by forming a wall thickness reducing part between a solid part in the vicinity of the extreme end and the upper end flange part combined with a piston, so that outer circumferential walls projected in the nearly same diameter as the solid part are provided on the thickness reducing part. SOLUTION: A driver blade 20 is formed so that the part from the percussion face on the extreme end to about 25mm distance is formed solid so as not to be deformed by a bending load applied to the vicinity of the extreme end, and the part from the solid part to the flage part combined with a piston 4 is cutout on the outer circumferential wall at four positions into a cross section and formed into the nearly same diameter of the projecting outer circumferential wall as that of the solid part. The mass of a piston assembly 27 combining together the piston 4 and the driver blade 20 is reduced. Reaction at driving is reduced by reducing the wall thickness of the driver blade 20 into a cross shape in this way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driver blade capable of reducing the mass while ensuring necessary strength.

[0002]

2. Description of the Related Art As a conventional example of a driving tool, Japanese Patent Application No. 7-82847 previously filed by the present applicant will be cited and described with reference to FIG. When the nail is inserted into the nail guide 23 and the tip of the nail is pressed against the material to be driven, the nail head pushes up the push lever 26 and unlocks the trigger 25. When the trigger 25 is pulled in this state, the trigger valve 11 operates and the compressed air in the head valve upper chamber 8 is released to the atmosphere via the air passages 10 and 12. As a result, the head valve 6 rapidly rises, the compressed air in the pressure accumulating chamber 2 flows in above the piston 4, and the piston 4 and the driver blade 20 suddenly descend, driving the nail in the nail guide 23.

The air below the piston 4 of the cylinder 3 flows into the return air chamber 14 through the communication hole 17. When the piston 4 passes through the communication hole 19 having the check valve 18, the compressed air above the piston 4 of the cylinder 3 flows into the return air chamber 14 from the communication hole 19. When a part of the compressed air that has flowed into the return air chamber 14 reaches the repetitive valve lower chamber 13 via the air passage 15, the repetitive valve 27 moves up and shuts off the air passage 10 and the air passage 12. Since the head valve upper chamber 8 and the pressure accumulating chamber 2 are communicated with each other via the air passage 16 which is vertically penetrating the head valve 6, the compressed air in the pressure accumulating chamber 2 flows in and the head valve upper chamber 8 and The pressure in the air passage 10 increases. The repetitive valve 27 does not descend because the upper pressure receiving area is smaller than the lower pressure receiving area, and maintains the state in which the air passage 10 and the air passage 12 are blocked.

The head valve 6 is lowered by the pressing force of the head valve spring 28 as the pressure of the head valve upper chamber 8 rises, shuts off the cylinder 3 and the pressure accumulating chamber 2, and removes the air above the piston 4 in the cylinder 3 from the exhaust valve 7. Release to atmosphere. Therefore, the compressed air in the return air chamber 14 returns the piston 4 to the initial top dead center. Due to the expansion of air, the pressure of the return air chamber 14 becomes low, the pressure of the repetitive valve lower chamber 13 communicating with the return air chamber 14 also becomes low, and the pressure of the repetitive valve upper chamber 9 causes the repetitive valve 27 to descend and the head. Compressed air in the valve upper chamber 8 and the air passage 10 is released to the atmosphere via the trigger valve 11. Since the passage cross-sectional area of the air passage 16 is set to be sufficiently smaller than the passage cross-sectional areas of the air passages 10 and 12, the amount of discharge from the trigger valve 11 is larger than that of the air filling from the air passage 16 and the head valve above The pressure in the chamber 8 drops rapidly. When the pressure in the head valve upper chamber 8 is lowered, the head valve 6 is again returned as described above.
Performs a series of operations such as rising and driving. These series of operations are repeated while the trigger 25 is operated, and the nail is driven into the material to be driven by repeatedly striking the nail 25.

[0005]

SUMMARY OF THE INVENTION In the above-mentioned driving machine,
When the piston 4 and the driver blade 20 rapidly reciprocate, a reaction force that moves the driving tool body 1 in a direction opposite to the reciprocal movement of the driver blade 20 is generated as a reaction. Due to this reaction, there are problems that the material to be driven is displaced, the nail guide 23 is disengaged from the nail being driven, and the holding hand is easily tired. If the outer diameter of the driver blade 20 is reduced to reduce the mass in order to reduce this recoil, there is a problem that the strength is insufficient and the driver blade 20 is damaged. Further, even if a hole is formed in the center of the driver blade 20 in the axial direction to make it hollow near the nail striking surface, the driver blade 20 having a relatively small diameter cannot reduce the mass and the reaction force cannot be greatly reduced. was there. An object of the present invention is to solve the conflicting problems described above and improve the operability, workability and durability of this type of driving machine.

[0006]

The above object is to provide at least three or more protruding outer peripheral walls having substantially the same diameter as the solid portion between the solid portion near the tip and the upper end flange portion connected to the piston. This is accomplished by forming the thinned portion so that it is present.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is shown in FIGS. Compressed air from a compressor (not shown) is accumulated in the pressure accumulating chamber 2 of the driving tool body 1. A cylindrical cylinder 3 is provided in the driving tool body 1, and a piston 4 is provided in the cylinder 3 so as to be vertically slidable. Piston ring 5 around piston 4
Is provided to seal between the cylinder 3 and the piston 4. A head valve 6 is provided at the upper end of the cylinder 3,
When the head valve 6 rises, the upper end of the cylinder 3 opens, the exhaust valve 7 closes, the accumulator chamber 2 communicates with the upper side of the piston 4 of the cylinder 3, and when the head valve 6 descends, the upper end of the cylinder 3 closes and the exhaust valve 7 opens. The upper side of the piston 4 of the cylinder 3 is adapted to communicate with the atmosphere. The head valve upper chamber 8 and the repetitive valve upper chamber 9 communicate with each other through an air passage 10, and the repetitive valve upper chamber 9 and the trigger valve 11 communicate with each other through an air passage 12. The repetitive valve lower chamber 13 and the return air chamber 14 communicate with each other via an air passage 15.

The head valve 6 is provided with an air passage 16 penetrating vertically, and when the head valve 6 descends, the cylinder 3
It is closed at the upper end, and when the head valve 6 rises, the head valve upper chamber 8 and the pressure accumulating chamber 2 communicate with each other. The passage cross-sectional area of the air passage 16 is set sufficiently smaller than the passage cross-sectional areas of the air passages 10 and 12. A communication hole 19 having a communication hole 17 and a check valve 18 is provided in the cylinder 3 so as to communicate with the return air chamber 14 as in the conventional driving machine.

A piston 4 is provided at the nail ejection portion of the driving machine body 1.
A blade guide 21 that guides the driver blade 20 integrally connected with the blade guide 2 that guides the nail 22.
Nail guide 23 that slides up and down along 1 and nail 22
Is inserted into the nail guide 23, and when the tip of the nail 22 is pressed against the material 24 to be driven, a push lever 26 that lifts up while being guided by the blade guide 21 and unlocks the trigger 25 is provided.

The driver blade 20 is solid about 25 mm from the striking surface of the tip so as not to be deformed by the bending load applied to the vicinity of the tip, and the solid portion to the flange portion connected to the piston 4 are shown in FIG. As shown, the outer peripheral wall is thinned at four locations so that the cross section has a cross shape, and the diameter of the protruding outer peripheral wall is formed to be substantially the same as that of the solid portion. The mass of the piston assembly 27 in which the piston 4 and the driver blade 20 are combined is 43 gf, which is about 20% less than the 53 gf in a circular (solid) state. It has been found that the recoil upon driving is proportional to the mass of the piston assembly 27. Therefore, by reducing the thickness to a cross shape, the recoil is also reduced by about 20%.

The reason why the required strength can be secured despite the reduced thickness will be described below. As shown in FIG. 6, the driver blade 20 is guided through the blade guide 21 at the position where the nail 22 is started to be driven. A force for compressing the driver blade 20 acts and the driver blade 20 tries to deform in the cylinder 3 as shown in the drawing. However, since the driver blade 20 is guided by the blade guide 21, the driver blade 20 is deformed. The possible distance is A.

The outer periphery of the driver blade 20 is thinned by reducing the entire circumference in the radial direction from a portion about 25 mm from the striking surface of the tip to the flange portion with the piston 4 so that the outer periphery of the driver blade 20 is the same as the mass of the cross-shaped driver blade 20. A cross section of the diameter is shown in FIG. Only part of the tip is guided by the blade guide 21, and the distance at which the driver blade 20 can be deformed is B. The buckling load of the driver blade 20 can be calculated as follows.

According to Euler's theory, Pcr = 2.05 × π ² × E × I / L ² where Pcr is the buckling load (Kg) of the driver blade 20.
f), E is the longitudinal elastic modulus (Kgf / mm ²⁾ , I is the second moment of area (mm ⁴ ), and L is the length (m in which the driver blade 20 is not supported by the blade guide 21).
m), which is A in FIG. 2 and B in FIG. 7.

The results of the above calculations are summarized in the following table.

[0015]

[Table 1]

If the mass of the driver blade 20 is the same, the strength of the cross-shaped driver blade 20 is about 18 times that of the thin driver blade 20 of FIG. Also, FIG.
Since the XX direction and YY direction co-buckling loads are the same, the same strength can be secured no matter which direction the load acts.

Generally, buckling occurs when the ratio of deformable axial length to diameter is 10 times or more. Therefore, by making the radial cross section of the driver blade 20 into a cross shape,
There is no possibility of damage due to buckling load. Further, it is effective to secure the strength by surely guiding a part of the outer peripheral wall of the driver blade 20 to the blade guide 21, that is, by reducing the thickness in a cross shape.

The driving operation by the driving machine having the above-mentioned structure is shown in FIGS.
This will be described with reference to FIG. When the nail 22 is inserted into the nail guide 23 and the tip of the nail 22 is pressed against the driven material 24, the head of the nail 22 pushes up the push lever 26 and the upper end of the push lever 26 unlocks the trigger 25. When the trigger 25 is pulled in this state, the compressed air of the head valve 6 is discharged from the trigger valve 11 via the air passages 10 and 12, the head valve 6 rises, and the compressed air rapidly goes to the upper side of the piston 4 of the cylinder 3. The driver blade 20, which is integrated with the piston 4 and suddenly descends. The driver blade 20 drives the nail 22 in the nail guide 23 while descending to near the piston bottom dead center. Driver blade 20
Although the nail 22 is driven by the driving resistance of the nail 22 and tries to buckle, since it is guided by the blade guide 21, the deformable distance is only A and the buckling does not occur.

When the compressed air that has flowed into the return air chamber 14 through the air passage 15 flows into the repetitive valve lower chamber 13, the repetitive valve upper chamber 9 is at atmospheric pressure, so that the repetitive valve 27 moves up, and the air passage 10 and the air The passage 12 is cut off. Since the head valve upper chamber 8 and the pressure accumulating chamber 2 communicate with each other through the air passage 16, the compressed air in the pressure accumulating chamber 2 flows in and the pressure in the head valve upper chamber 8 and the air passage 10 rises. The repetitive valve 27 maintains the state in which the air passage 10 and the air passage 12 are blocked because the upper pressure receiving area is smaller than the lower pressure receiving area.

The head valve 6 lowers due to the pressing force of the head valve spring 28 as the pressure in the head valve upper chamber 8 rises, shuts off between the cylinder 3 and the pressure accumulating chamber 2, and removes the air above the piston 4 of the cylinder 3 from the exhaust valve 7. Released into the atmosphere. As a result, the compressed air in the return air chamber 14 returns the piston 4 to the initial top dead center. Due to the expansion of air, the pressure in the return air chamber 14 becomes low, and the pressure in the communicating repetitive valve lower chamber 13 also becomes low. The pressure in the repetitive valve upper chamber 9 causes the repetitive valve 27 to descend, and the compressed air in the head valve upper chamber 8 and the air passage 10 is transferred to the trigger valve 1
It is released to the atmosphere via 1.

The passage sectional area of the air passage 16 is equal to that of the air passage 1.
Since it is set to be sufficiently smaller than the passage cross-sectional areas of 0 and 12, the amount of discharge from the trigger valve 11 becomes larger than the air filling of the air passage 16, and the pressure in the head valve upper chamber 8 drops rapidly. When the pressure in the head valve upper chamber 8 drops, a series of operations such as raising and driving of the head valve 6 are performed again as described above. Then, the nail 22 is driven into the driven material 24 by repeatedly striking the nail 22 many times.

When the trigger 25 is released contrary to the above-described operation, the head valve upper chamber 8 is filled with the compressed air in the pressure accumulating chamber 2 from the trigger valve 11 through the air passages 12, 10.
As shown in FIG. 1, the head valve 6 descends, and the piston assembly 27 stops the driving operation at the position where it has returned to the top dead center. Further, the push lever 26 and the nail guide 23 are lowered as shown in FIG. 1 to lock the trigger 25.

FIG. 8 shows another embodiment of the driver blade 20 of the present invention. A hole along the axial direction is provided in the thinned portion which is not a solid portion so as to further reduce the mass of the driver blade 20. It was done. FIG. 9 shows still another embodiment of the driver blade 20 of the present invention, in which two small diameter portions are provided between the solid portion and the flange portion, and the solid portion is almost formed between these small diameter portions. A large diameter portion having the same diameter is provided to reduce the mass.

[0024]

As described above, according to the present invention, by providing the driver blade with an appropriate thinned portion so as to balance the mass and the strength, it is possible to reduce the recoil due to the weight reduction of the driver blade and to cause the conflict. It is possible to secure the strength of the driver blade, which is a problem.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a driving machine adopting a driver blade of the present invention.

FIG. 2 is an enlarged sectional view of an essential part of FIG. 1 showing a driving start state.

FIG. 3 is an enlarged cross-sectional view of a main part of FIG. 1 showing a state where a driver blade is at bottom dead center.

FIG. 4 is a side view and a sectional view taken along line C-C showing an embodiment of a driver blade of the present invention.

FIG. 5 is a sectional view showing an example of a conventional driving tool.

FIG. 6 is an explanatory sectional view showing a buckling state of the driver blade of the present invention.

FIG. 7 is a cross-sectional view showing a state in which a virtual driver blade having a small diameter is buckled.

FIG. 8 is a side view and a sectional view taken along line EE showing another embodiment of the driver blade of the present invention.

FIG. 9 is a side view and a sectional view taken along line FF showing another embodiment of the driver blade of the present invention.

[Explanation of symbols]

Reference numeral 1 is a driver main body, 3 is a cylinder, 4 is a piston, 20 is a driver blade, 21 is a blade guide, and 27 is a piston assembly.

Claims (2)

[Claims] 1. A piston provided for reciprocating in a cylinder provided in a driver body, a substantially cylindrical driver blade having an upper end coupled to the piston, and a blade guide for guiding reciprocating movement of the driver blade. , In the driving machine that hits the stopper head with the tip of the driver blade to drive the stopper, between the solid portion near the tip and the upper flange connected to the piston is almost the same as the solid portion. A driver blade for a driving machine, characterized in that the thinned portion is formed so that there are at least three outer peripheral walls having a protruding diameter. 2. A piston which reciprocates in a cylinder provided in a driving tool body, a substantially cylindrical driver blade having an upper end coupled to the piston, and a blade guide which guides the reciprocating movement of the driver blade. , In the driving machine that hits the stopper head with the tip of the driver blade to drive the stopper, between the solid portion near the tip and the upper flange connected to the piston is almost the same as the solid portion. A driver blade for a driving machine, characterized in that a large-diameter portion of the diameter and small-diameter portions are formed on both upper and lower sides of the large-diameter portion.