JP5110301B2 - Pneumatic tool - Google Patents

Description

  The present invention provides a driving force adjusting mechanism that switches strength of a driving force when driving a fastener such as a nail and a driving screw in a pneumatic tool such as a nailing machine, a screw driving machine, and a screwing machine that uses compressed air as a driving source. It has a pneumatic tool.

  Generally, a pneumatic screw driving machine is designed to lightly drive a driving screw into a material to be driven and then tighten it firmly. According to such driving and screw tightening processes, each of the driving screws hits the driving screw. A mechanism and a screw tightening mechanism for rotating the driving screw are provided. The striking mechanism is configured such that a driver bit is integrally coupled to a striking piston slidably accommodated in a striking cylinder, a main valve is actuated by a trigger operation, and a main air chamber for storing compressed air is provided to the striking cylinder. The compressed air is supplied to the striking cylinder to drive the striking piston. Conventionally, the supply amount of the compressed air is always constant, so that the striking force by the striking piston is always constant. At the time of driving, it is necessary that the tip of the driving screw penetrates the upper material and is driven to the middle of the base.

  However, for example, even if the upper material constituting the material to be driven is a gypsum board, there are cases where the base is a wooden plate and a thin steel plate. Since the wooden board is softer than the thin steel sheet, the energy for driving the driving screw through the upper member and driving it halfway through the wooden board may be smaller than that of the steel sheet. However, it is not sufficient to pierce the thin steel plate with the tip of the driving screw with this driving energy. On the other hand, when the driving energy is matched to the thin steel plate, when the driving screw is driven into the wood board base with this driving energy, the driving screw penetrates the wooden board, or the displacement due to the reaction force of the screw driving machine, etc. However, the tip of the driver bit cannot be engaged with the head groove of the driving screw, resulting in inconvenience of screw tightening failure.

  In view of this, there is known a pneumatic tool provided with a driving force adjusting mechanism of a pneumatic screw driving machine capable of adjusting a driving force to always make a driving depth of a driving screw appropriate for a workpiece. For example, in Patent Document 1, the air supply port for supplying compressed air from the main air chamber is formed in two upper and lower stages, and when the switching valve is operated upward, the upper and lower air supply ports are opened. When operated downward, the upper air supply port is closed and only the lower air supply port is opened, and the driving force is adjusted according to the air supply amount.

  However, the above technique has a problem that the overall height of the pneumatic tool becomes too high, and a valve stopper that suppresses the valve stroke is deformed, so that even if the weak mode is set, the strong mode is switched.

Accordingly, the one of Patent Document 2 has been developed correspondingly. In this configuration, air supply ports having different cross-sectional areas are provided not inside and outside, but one of the air supply ports is opened by moving the switching valve up and down. That is, an operating lever having one end pivotally supported at the upper part of the impact cylinder is provided so as to be able to swing in the left-right direction. Are engaged. According to the above configuration, the operating shaft slides along the guide groove by swinging the operation lever to the left and right, and the air supply port having a different size depending on whether the operation shaft moves to the upper part or the lower part. Can be selectively opened.
Japanese Patent No. 3520443 JP2007-326203A

  However, in the above switching method, the amount of vertical stroke is insufficient, the switching valve does not operate sufficiently, and a predetermined driving force may not be obtained. As a solution to this, the inclination of the guide groove may be tightened or may be increased without changing the gradient of the guide groove. However, in the former case, the operation lever is difficult to operate. In the latter case, the left and right swing angle of the operation lever has to be increased, but this is difficult because of the structural limitation of the amount of rotation of the operation lever.

  It is an object of the present invention to solve the above-mentioned problems and to provide a pneumatic tool provided with a driving force adjusting mechanism that can keep the overall height low and can secure a sufficiently large vertical stroke amount of the switching valve. To do.

In order to solve the above-mentioned problem, the invention according to claim 1 provides a striking cylinder by providing a main air chamber storing a compressed air and a striking cylinder in the tool body, and supplying the compressed air from the main air chamber to the striking cylinder. When driving a striking piston slidably housed inside and driving a fastener, a valve housing is provided between the striking cylinder and the cylinder cap above it, and the switching valve moves up and down in the valve housing. Pneumatic pressure that can be freely accommodated and that is provided between the main air chamber and the striking cylinder by the vertical movement of the switching valve to selectively open and close air supply ports having different cross-sectional areas to obtain different driving forces. In the tool, a valve housing is provided between the hitting cylinder and the cylinder cap on it. A switching valve is accommodated in the valve housing so as to be movable up and down, and the air supply port provided between the main air chamber and the striking cylinder is selectively opened and closed by the vertical movement of the switching valve. The operating rod protrudes upward from the center of the switching valve, passes through the cylinder cap, and a guide pin is provided at the upper end of the operating rod in a direction perpendicular to the axis of the operating rod. An annular switching dial is provided on the upper portion of the cylinder cap so as to be rotatable around the operating rod. A guide groove having an inclined middle is formed on a side wall portion of the switching dial, and the guide pin is connected to the guide groove. The guide pin is slidably engaged from one end to the other end, and the guide pin is engaged with a detent. .

  The invention according to claim 2 is characterized in that, in claim 1, a dial guide for guiding the rotation of the switching dial is provided around the switching dial, and the dial guide is provided with a detent for the guide pin. To do.

  According to a third aspect of the present invention, in the first or second aspect, the air supply port passes through the first air supply port having a large cross-sectional area formed through the lower portion of the side wall of the valve housing and the valve. A second air supply port having a small cross-sectional area formed, the switching valve is movably provided above and below the first air supply port, and the compressed air from the main air chamber receives the first air supply port. 1 is provided so as to be able to be supplied to the outside of the air supply port.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, when the switching valve reaches a bottom dead center, a small clearance is formed between the outer peripheral surface of the switching valve and the inner wall of the valve housing. It is characterized by that.

  The invention according to claim 5 is characterized in that, in claim 4, the clearance is such that the sealing O-ring is removed from the outer peripheral surface of the switching valve.

The invention according to claim 1 is configured to selectively open and close air supply ports having different cross-sectional areas provided between the main air chamber and the impact cylinder by the vertical movement of the switching valve, and the center of the switching valve. The operating rod protrudes upward from the cylinder cap and passes through the cylinder cap . A guide pin is provided at the upper end of the operating rod in a direction perpendicular to the axis of the operating rod, while the upper portion of the cylinder cap is annular. The switching dial is rotatably provided around the operating rod, and a guide groove having an inclined middle is formed on the side wall of the switching dial, and the guide pin is slidably engaged along the guide groove. The guide pin is engaged with the rotation stopper. Therefore, when the switching dial is rotated, the guide groove moves in the same direction, so that the guide pin slides along the guide groove and is moved in the vertical direction. When the guide pin moves up and down, the operating rod also moves up and down. As the switching valve moves up and down in this way, the air supply port provided between the main air chamber and the striking cylinder is selectively opened and closed. You can choose the magnitude of the power.

  According to the above configuration, since the height difference between the air supply ports having different cross-sectional areas is small, the overall height can be kept low. In addition, since the switching valve is moved up and down by rotating the switching dial, there is no need to increase the switching dial. Further, since the guide groove is formed in an arc shape in a plan view on the side wall portion of the annular switching dial, the guide groove becomes longer if replaced with a straight line. Therefore, even if the inclination gradient of the guide groove is not stiff, it is possible to ensure a sufficiently large amount of up / down stroke of the switching valve only by adjusting the rotation amount of the switching valve.

  According to the invention according to claim 2, since the dial guide for guiding the rotation of the switching dial is provided around the switching dial, and the dial guide is provided with the detent of the guide pin, the dial guide rotates the switching dial. The guide pin can also be used as a detent.

  According to the invention of claim 3, the air supply port has a small cross-sectional area formed through the first air supply port having a large cross-sectional area penetratingly formed in the lower portion of the side wall of the valve housing and the valve. The switching valve is movably provided above and below the first air supply port, and the compressed air from the main air chamber is outside the first air supply port. Since the first air supply port opens when the switching valve moves to the lower part and the second air supply port opens when the switching valve moves to the upper part. A mode can be selected.

  According to the invention of claim 4, when the switching valve reaches the bottom dead center, a small clearance is formed between the outer peripheral surface of the switching valve and the inner wall of the valve housing. Even in this case, since a small clearance is formed between the outer peripheral surface of the switching valve and the inner wall of the valve housing, the driving force can be prevented from dropping greatly even in the weak mode.

  According to the fifth aspect of the present invention, since the clearance is such that the sealing O-ring is removed from the outer peripheral surface of the switching valve, the supply amount of compressed air supplied from the clearance is not large.

  In the following, an embodiment of a pneumatic tool according to the present invention will be described with reference to the drawings with a screw driving machine. In addition, it is not limited to a pneumatic tool screw driving machine. What is necessary is just to drive using compressed air, for example, a general nailing machine etc. may be sufficient.

  As shown in FIG. 1, the screw driving machine operates the trigger valve 3 by pulling the trigger 2 provided on the tool body 1, and the main valve 4 moves up in conjunction with the trigger valve 3. The chamber 5 is opened with respect to the striking cylinder 6, and the compressed air in the main air chamber 5 is supplied to the top of the striking cylinder 6, and the striking piston 7 is driven by this air pressure, and is integrally coupled with the striking piston 7. The driver bit 8 is struck downward so that a driving screw (not shown) supplied from the magazine 10 into the nose portion 11 is driven into the object to a certain depth. The driver bit 8 is rotated by a rotary gear 13 driven by an air motor 12 and is configured to further rotate a driven driving screw and screw it into an object.

  By the way, in the screw driving machine, a driving force adjusting mechanism capable of adjusting the driving force by adjusting the amount of compressed air supplied from the main air chamber 5 to the driving cylinder 6 is provided on the upper portion of the cylinder cap 14. ing.

  That is, as shown in detail in FIGS. 2A and 3, a piston stop 15 that holds the striking piston 7 at the top dead center is disposed between the striking cylinder 6 and the cylinder cap 14 thereon. Yes. The piston stop 15 is formed in a cylindrical shape, an engagement claw 16 that engages and holds the bulging portion at the upper end of the striking piston 7 is formed at a constant interval, and a valve housing 17 is provided in the middle portion. A fitting hole 18 is formed in the upper portion of the valve housing 17 and the center of the cylinder cap 14.

  A switching valve 20 is accommodated in the valve housing 17 so as to be movable up and down. An operating rod 21 protrudes upward from the center of the switching valve 20. The operating rod 21 passes through the fitting hole 18. An O-ring 22 is attached to the outer periphery of the switching valve 20. When the switching valve 20 is moved to the bottom dead center, the O-ring 22 comes into contact with the lower edge 23 of a slightly smaller diameter at the lower part of the valve housing 17 to be in a sealed state, but the switching valve 20 is located above that. In some cases, a small clearance is formed between the O-ring 22 of the switching valve 20 and the inner wall of the valve housing 17.

  On the other hand, a first air supply port 24 is formed in the lower portion of the side wall of the valve housing 17. A second air supply port 25 is formed through the center of the switching valve 20 and the operating rod 21. The first air supply port 24 has a larger cross-sectional area than the second air supply port 25.

  Next, a guide pin 26 is provided on the upper portion of the operating rod 21 that protrudes upward through the cylinder cap 14 so as to intersect in the orthogonal direction.

  A switching dial 27 made of synthetic resin is provided on the upper portion of the cylinder cap 14 so as to be rotatable around the operating rod 21 in the horizontal direction. The switching dial 27 has an annular shape, and an operation lever 28 projects from one side of the side wall portion. A Z-shaped switching guide groove 30 having an inclined middle portion is formed on the opposite side of the side wall portion. . As shown in FIGS. 4A and 5B, the guide groove 30 is formed by inclining an upper step portion 30b at one end of the inclined portion 30a and a lower step portion 30c at the other end, and the guide pin 26 is a guide. The inside of the groove 30 is slidably engaged.

  Further, a dial guide 31 made of synthetic resin is provided on the outer periphery of the switching dial 27. The inner peripheral surface of the dial guide 31 is formed to be slidable on the outer peripheral surface of the switching dial 27, and the switching dial 27 is configured to be guided along the dial guide 31 and rotate.

  A fixed cover 32 is disposed above the dial guide 31, and a screw 33 passing through the dial guide 31 from the fixed cover 32 is screwed to the mounting leg 34 of the cylinder cap 14, thereby fixing the dial guide 31. A switching dial 27 is rotatably guided inside the dial guide 31.

  The dial guide 31 is formed with an engaging groove 35 that engages with the guide pin 26. The engagement groove 35 constitutes a detent of the operating rod 21 by engaging with the guide pin 26.

  Reference numeral 36 denotes a cylinder cap protector. An opening 39 is formed on one side of the cylinder cap protector 36, the operation lever 28 of the switching dial 27 is disposed inside the opening 39, and its end is exposed to the outside. For this reason, the operation lever 28 can be rotated in the left-right direction from the outside of the cylinder cap protector 36.

  According to the above configuration, when the switching dial 27 is rotated in the left-right direction together with the operation lever 28, the guide pin 26 moves along the guide groove 30 because the Z-shaped guide groove 30 moves left and right in the guide pin 26 portion. The upper stage part 30b slides to the lower stage part 30c and moves in the vertical direction accordingly. When the guide pin 26 moves up and down, the operating rod 21 also moves up and down.

  When the strong mode is selected, the switching dial 27 is rotated to move the guide pin 26 upward to the upper step portion 30b of the guide groove 30 as shown in FIGS. 4 (a) and 5 (a). As a result, as shown in FIG. 2A, the operating rod 21 moves upward, and the switching valve 20 moves above the first air supply port 24, so that the compressed air from the main air chamber 5 is The air is supplied into the striking cylinder 6 through the first air supply port 24. In addition, since there is a clearance between the O-ring 22 of the switching valve 20 and the inner peripheral surface of the valve housing 17, a part of the compressed air passes through this clearance, and the impact cylinder 6 also passes through the second air supply port 25. Supplied in. In this case, a large amount of compressed air is supplied, and a large driving force is obtained.

  On the other hand, when the weak mode is selected, the switching dial 27 is rotated in the reverse direction to move the guide pin 26 to the lower step portion 30c of the guide groove 30 as shown in FIGS. 4B and 5B. . As a result, as shown in FIG. 2B, the operating rod 21 moves downward, the switching valve 20 moves below the first air supply port 24, and the O-ring 22 on the outer periphery of the switching valve 20. Is sealed against the lower edge 23 of the valve housing 17. Therefore, the compressed air from the main air chamber 5 is supplied into the striking cylinder 6 through the second air supply port 25 only. In this case, since only a small amount of compressed air is supplied compared to the case where the operating rod 21 moves up, the driving force is small.

  Thus, the magnitude of the driving force can be selected by adjusting the supply amount of the compressed air by operating the operation lever 28.

  As described above, according to the driving force adjusting mechanism, since the height difference between the first air supply port 24 and the second air supply port 25 is small, the overall height can be kept low. Further, since the switching valve 20 is moved up and down by rotating the switching dial 27, it is not necessary to enlarge the switching dial 27. Further, since the guide groove 30 is formed in an arc shape in a plan view on the side wall portion of the annular switching dial 27, the guide groove 30 becomes longer if replaced with a straight line. Therefore, even if the inclination gradient of the guide groove 30 is not tightened, it is possible to ensure a sufficiently large amount of up / down stroke of the switching valve 20 only by adjusting the rotation amount of the switching valve 20.

  If the driving force is too weak in the weak mode, for example, with a driving screw, the pneumatic tool for driving the driving screw may momentarily float due to the reaction force immediately after driving, and the nose portion 11 may be displaced forward. A cam-out phenomenon that easily disengages from the driving screw is likely to occur.

  In this case, as shown in FIG. 6, the sealing O-ring may be removed from the outer peripheral surface of the switching valve 20. When the switching valve 20 reaches the bottom dead center, a small clearance is formed between the outer peripheral surface of the switching valve 20 and the lower edge 23 of the valve housing 17, and compressed air also enters the striking cylinder 6 from here. Since it leaks, the driving force does not drop greatly.

Longitudinal sectional view of a screw driving machine according to the present invention (A) and (b) are explanatory drawings of the operation mode of the driving force adjusting mechanism. Disassembled perspective view of the periphery of the cylinder cap (A) and (b) are perspective views showing a switching mode between a strong mode and a weak mode of the driving force adjusting mechanism. (A) (b) is a top view which shows the switching mode of the strong mode and weak mode of a driving force adjustment mechanism Partial enlarged sectional view showing another form of switching valve

6 Stroke cylinder 15 Dial guide 14 Cylinder cap 17 Valve housing 20 Switching valve 21 Actuating rod 24, 25 Air supply port 26 Guide pin 27 Switching dial 30 Guide groove

Claims (5)

A tool body is provided with a main air chamber storing compressed air and a striking cylinder, and by supplying compressed air from the main air chamber to the striking cylinder, a striking piston slidably accommodated in the striking cylinder is driven. When driving a fastener, a valve housing is provided between the striking cylinder and the cylinder cap on the cylinder, and a switching valve is accommodated in the valve housing so as to be movable up and down, and the main air chamber is moved by the vertical movement of the switching valve. In the pneumatic tool which is provided between the impact cylinder and the impact cylinder and which selectively opens and closes the air supply port having different cross-sectional areas to obtain different impact forces,
The operating rod protrudes upward from the center of the switching valve, passes through the cylinder cap, and the upper end of the operating rod is provided with a guide pin perpendicular to the axis of the operating rod ,
An annular switching dial is rotatably provided around the operating rod at the upper portion of the cylinder cap. A guide groove having an inclined middle is formed on a side wall portion of the switching dial, and the guide pin is connected to one end of the guide groove. A pneumatic tool characterized in that it is slidably engaged with the other end and the guide pin is engaged with a detent.   2. The pneumatic tool according to claim 1, wherein a dial guide for guiding the rotation of the switching dial is provided around the switching dial, and the dial guide is provided with a detent for the guide pin.   The air supply port includes a first air supply port having a large cross-sectional area formed in a lower portion of the side wall of the valve housing, and a second air supply port having a small cross-sectional area formed in the valve and penetrating therethrough. And the switching valve is movably provided above and below the first air supply port, and the compressed air from the main air chamber is provided outside the first air supply port. The pneumatic tool according to claim 1 or 2, characterized in that.   The small clearance is formed between the outer peripheral surface of the switching valve and the inner wall of the valve housing when the switching valve reaches the bottom dead center. Pneumatic tool.   5. The pneumatic tool according to claim 4, wherein the clearance is set such that a sealing O-ring is removed from an outer peripheral surface of the switching valve.

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