WO2005014231A1

WO2005014231A1 - Compressed air-driven screw tightening machine

Info

Publication number: WO2005014231A1
Application number: PCT/JP2004/011636
Authority: WO
Inventors: Takeo Fujiyama; Junichi Tamura; Masafumi Satsuka; Hideki Okushima
Original assignee: Max Co., Ltd.
Priority date: 2003-08-12
Filing date: 2004-08-06
Publication date: 2005-02-17
Also published as: JP2005059143A; JP4277618B2

Abstract

A compressed air-driven screw tightening machine adapted to supply compressed air to an air motor (4) to rotatively drive a driver bit (9) and, concurrently therewith, to propel the driver bit (9) in the screw tightening direction, so as to the screw, wherein an exhaust path (24) for discharging into the atmosphere the compressed air discharged from the air motor (4) is provided with an exhaust control valve (30) for variably controlling the cross-sectional area of the exhaust path (24). The exhaust control valve (30) variably controls the amount of air being discharged from the air motor (4).

Description

4 011636

Technical field of compressed air driven screw tightening machine

According to the present invention, a driver bit, which is rotationally driven by an air motor, is engaged with a screw to rotate the screw, and at the same time, compressed air is applied to a bistone formed integrally with the dry bit to drive and move the dry light bit. The present invention relates to a compressed air driven screw tightening machine driven by compressed air for screwing a screw into a work material.

Rice field

In particular, the present invention relates to a cam-art prevention mechanism of a compressed air driven screw tightening machine for preventing a cam-art phenomenon in which a driver bit deviates from a recess formed in a screw head. Background art

An air motor is rotationally driven using compressed air as a power source, and a driver bit rotationally driven by the air motor is engaged with a screw to rotate the screw in a screwing direction, and a piston integrally connected to the driver bit is rotated. 2. Description of the Related Art There is known a compressed air driven screw tightening machine which is slidably housed in a cylinder, and in which compressed air introduced into the cylinder acts on the piston to drive a driver bit in a screwing direction. In the above-mentioned conventional screw tightening machine, the compressed air for rotating the driver bit is supplied from the air chamber formed inside the grip portion through the starting pulp operated by the finger of the hand holding the drip portion. Supplied to the air motor. The air supplied to the air motor and driving the air motor is discharged from the air motor outlet and discharged to the atmosphere via a silencer provided at the rear of the screw tightening machine.

In conventional screw tightening machines, this is necessary to ensure the tightening torque and screw tightening speed for tightening the largest screw (for example, a screw with a length of about 9 Omm) used in the screw tightening machine. An air motor is mounted. So, for example, For example, it is possible to tighten screws from the shortest screw of about 41 mm to the maximum screw with one machine. As the torque output to the driver bit corresponds to the maximum screw, as a result, when using a short screw with a shallow recess, the driver bit is repelled after picking up the recess and coming off the recess. A phenomenon called come out occurs. When this cam-out phenomenon occurs, there has been a problem that the screw is not tightened to a predetermined depth and the head of the screw floats. Therefore, conventionally, the supply amount of the compressed air to the air motor is variably adjusted so that the rotation speed and torque of the air motor can be variably adjusted in accordance with the size of the screw to be used. However, in this case, the performance of the silencer cannot cope with fluctuations in the displacement of the compressed air discharged from the air motor. As a result, there has been a problem that the output performance of the air motor is reduced or the silencing performance of the silencer is reduced.

To solve this problem, Japanese Patent Publication No. 26954329/29 discloses a screw tightening machine that variably adjusts the amount of compressed air supplied to an air motor in accordance with the size of a screw to be used. We have proposed a screw tightening machine equipped with an exhaust port opening area variable mechanism that adjusts the opening area of the exhaust port for exhausting compressed air exhausted from the air to the atmosphere. When the amount of compressed air supplied to the air motor is large, the opening area of the exhaust port is increased to increase the exhaust capacity from the exhaust port, and when the amount of compressed air supplied to the air motor is small, the opening area of the exhaust port is reduced. By reducing the exhaust capacity from the exhaust port, the output performance of the air motor and the silencing performance of the silencer are maintained in good condition.

However, the screw tightening machine disclosed in Japanese Patent No. 2695432 has a speed adjusting mechanism for adjusting the speed of the air motor by adjusting the amount of compressed air supplied to the air motor. An exhaust port opening area variable mechanism for adjusting the amount of compressed air exhausted to the atmosphere via the port is provided, and the exhaust port opening area variable mechanism is operated in conjunction with the speed adjustment mechanism. It is necessary to link with. For this reason, the structure of the screw tightening machine was complicated, and the size of the screw tightening machine was increased. As a result, the weight and production cost of the screw tightening machine increased. Disclosure of the invention

The present invention solves the above-mentioned problems in the prior art, and can adjust the output torque of the air motor with a simple configuration, and efficiently muffles the exhaust noise of the compressed air exhausted from the air motor. An object of the present invention is to provide a compressed air driven screw tightening machine as described above.

In order to solve the above-mentioned problems, a compressed air driven screw tightening machine according to the present invention includes a driver bit engaged with a head portion of the screw to rotate the screw, and a piston adapted to propel the driver bit in an axial direction. Slidably housed therein, and an air motor driven by compressed air pressure for rotationally driving the driver bit, supplying compressed air to the air motor to rotate the driver bit, and Compressed air exhausted from the air motor is exhausted to the atmosphere in a compressed air driven screw tightening machine in which compressed air is introduced into the cylinder to drive the driver bit in the screwing direction and screw in the screw. An exhaust adjustment valve for variably adjusting the cross-sectional area of the exhaust path, and the exhaust adjustment valve is provided by the exhaust adjustment valve. The amount of exhaust air discharged from the Amota characterized by being adapted to variably adjusted.

The purpose of efficiently adjusting the output torque of the air motor and silencing exhaust noise due to exhaust air is to provide an exhaust path from the air motor with an exhaust adjustment valve that allows the cross-sectional area of the exhaust path to be variably adjusted from outside. It was realized. Brief Description of Drawings

FIG. 1 is a vertical side view of a compressed air driven screwdriver according to an embodiment of the present invention. FIG. 2 is a vertical front view of the compressed air driven screwdriver of FIG.

Fig. 3 is an enlarged vertical sectional front view of the main part of the compressed air driven screw tightening machine of Fig. 1. Fig. 4 is a side view of the exhaust control valve used in the compressed air driven screw tightening machine. Fig. 5 is a perspective view of the exhaust control valve of Fig. 4. 6A, 6B, 6C, and 6D show variable states of the cross-sectional area of the exhaust passage by the exhaust adjustment valve, and FIG. 6A shows a state in which the passage is fully opened. B is a state in which the cross-sectional area of the flow path is slightly reduced, FIG. 6C is a state in which the cross-sectional area of the flow path is further reduced, and FIG. Indicates the state of exhaust.

FIG. 7 is a vertical side view showing details of the impact mechanism. 1 is a compressed air drive screw tightening machine, 4 is an air motor, 5 is an impact mechanism, 9 is a driver bit, 23 is an exhaust cover, 24 is an exhaust passage, 25 is an exhaust passage, and 30 is an exhaust adjustment valve. Reference numeral 31 denotes an operation dial, and reference numeral 32 denotes a plate-shaped valve body. BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a compressed air driven screw tightening machine according to an embodiment of the present invention. The compressed air drive screw tightening machine 1 houses an air motor 4 that is rotationally driven by compressed air in a housing 2 in which a drip portion 3 is formed in a body. Below the air motor 4, an impact mechanism 5 composed of a hammer 6 rotated by the air motor 4 and an anvil 7 hit by the hammer 6 is accommodated. The rotary drive shaft 8 rotated by the anvil 7 of the impact mechanism 5 is housed in a hollow formed at the center of the impact mechanism 5 and the air motor 4, and is slidably disposed in the axial direction. At the lower end of the rotary drive shaft 8, a driver bit 9 to be engaged with a recess formed in the head of the screw is mounted. As the rotary drive shaft 8 rotates, the dry pavit 9 rotates.

A piston 10 is provided at a lower end of the rotary drive shaft 8. The piston 10 is slidably accommodated in a cylinder 11 formed below the impact mechanism 5 in the housing 2 along the axial direction of the driver bit 9. The compressed air supplied to the upper surface of the piston 10 in the cylinder 11 operates the piston 10 in the direction of the bottom dead center. As a result, the rotary drive shaft 8 The mounted driver bit 9 is operated integrally with the piston 10 toward the bottom dead center, and the screw engaged with the bit is propelled in the screwing direction.

Below the housing 2, a nose portion 12 for guiding a screw toward a workpiece is attached. The screw supplied to the nose portion 12 via the supply mechanism 13 provided on the rear side of the nose portion 12 engages with the driver bit 9. When the driver bit 9 moves toward the tip of the nose 12, the screw is pinched by a pair of chuck mechanisms 14 formed at the tip of the nose 12, and the screw is driven by the rotation and advancement of the driver bit 9. Screwed into the material.

Inside the grip part 3, an air chamber 16 connected to a compressed air source via an air plug 15 attached to the rear end of the grip part 3 is provided. The compressed air in the chamber 16 is supplied to the air motor 4 and the cylinder 11 via a starting valve 17 provided at the base of the drip section 3. As a result, the screw driving machine is driven. The starting valve 17 includes a trigger lever 18 operated by a finger holding the grip portion 3, and a starting mechanism 19 operated by pressing the nose portion 12 against the material to be driven. As shown in FIG. 3, an air supply passage 20 for compressed air supplied to the air motor 4 for driving the air motor 4 is connected to the start valve 17. For this reason, by operating the starting pulp 17, the compressed air in the air chamber 16 is supplied to the air motor 4 via the air supply path 20, and the air motor 4 is driven to rotate. Further, the rotary drive shaft 8 is rotated by the air motor 4 via the impact mechanism 5, and the driver bit 9 is driven to rotate. The compressed air that drives the air motor 4 passes from the outlet 22 formed in the outer peripheral wall 21 of the air motor 4 through the exhaust passage 24 formed in the exhaust cover 23 內, and further into the housing 2. The exhaust gas is discharged to the atmosphere from an exhaust port 26 formed at the rear end of the drip portion 3 via an exhaust passage 25 formed in the drip portion 3. A muffler 27 is provided at the exhaust port 26 to muffle the exhaust noise.

The exhaust path 24 formed in the exhaust cover 23 includes an exhaust path 24 An exhaust adjustment valve 30 for variably adjusting the cross-sectional area of the flow path is provided. The exhaust adjustment valve 30 is disposed downstream of the exhaust port 22 formed in the outer peripheral wall 21 of the air motor 4 and upstream of the exhaust port 26.

As shown in FIGS. 4 and 5, the exhaust adjustment valve 30 is provided with a rotation operation dial 31 at the upper end. The operation dial 31 is arranged outside the exhaust cover 23, and is arranged so as to be rotatable at an arbitrary position by an operator. A plate-shaped valve element 32 is provided at the center of the exhaust control valve 30. The plate-shaped valve element 32 is accommodated in a cylindrical valve chamber 28 formed in a middle part of the exhaust passage 24 in the exhaust cover 23. A predetermined flow cross-sectional area is formed between the rotation angle of the plate-shaped valve body 32 and the peripheral wall surface of the cylindrical valve chamber 28, and the amount of exhaust air flowing through the exhaust path 24 is adjusted. At the center of the plate-shaped valve element 32, an opening 33 for forming a minimum cross-sectional area when the exhaust path 24 in the exhaust cover 23 is completely shut off by the 扳 -shaped valve element 32 is formed. It is formed.

As shown in FIG. 6A, the flow path of the exhaust path 24 is set in a state where the plate-shaped valve element 32 is disposed in The cross-sectional area is maximized, and the flow rate of the exhaust air flowing through the exhaust passage 24 in the exhaust cover 23 is maximized. Therefore, the compressed air flows through the air motor 4 to the maximum, and the air motor 4 is driven to rotate at the maximum torque. As shown in FIG. 6B, the plate-shaped valve element 32 is rotated in the cylindrical valve chamber 28 and is arranged to be inclined with respect to the exhaust path 24 in the power member 23. However, the cross-sectional area of the exhaust path 24 is reduced, and the amount of exhaust air flowing through the exhaust path 24 in the exhaust cover 23 is limited. As a result, the amount of compressed air flowing through the air motor 4 is limited, and the air motor 4 is rotationally driven with a small torque.

As shown in FIG. 6C, the plate-shaped valve body 32 is further rotated so that one side edge of the plate-shaped valve body 32 is brought into sliding contact with the peripheral wall surface of the cylindrical valve chamber 28 to further increase the pressure. The cross-sectional area of the exhaust passage 24 is reduced, and the amount of exhaust air flowing through the exhaust passage 24 is limited. As a result, the amount of compressed air flowing through the air motor 4 is further reduced, and the air motor 4 is rotated with a smaller torque. Further, the plate-shaped valve body 32 is rotated so that both side edges of the plate-shaped valve body 32 are tilted so as to be in sliding contact with the peripheral wall surface of the cylindrical valve chamber 28 as shown in FIG. 6D. 1636

Then, the exhaust path 24 is blocked by the plate-shaped valve element 32, and the exhaust air is exhausted only through the opening 33 formed in the plate-shaped valve element 32. The sectional area of the opening 33 is set so that the output torque of the air motor 4 driven by the amount of exhaust air exhausted through the opening 33 corresponds to the tightening torque of the smallest screw used in the screw tightening machine 1. ing.

As shown in FIG. 3, the plate-shaped valve element 32 of the exhaust adjustment valve 30 is provided on the outer peripheral surface on the base side of the operation dial 31 formed on the upper part of the exhaust adjustment valve 32. A groove 34 corresponding to the rotation position of the operation dial 31 rotated to each position shown in FIGS. 6A to 6D is formed. The exhaust cover 23 is provided with a locking means 29 which is opposed to the concave groove 34 of the operation dial 31 and is urged to project toward the concave groove 34. The engaging means 29 engages with the respective concave grooves 34 of the operation dial 31 to lock the operation dial 31 at each rotation position, whereby the plate-shaped valve body 32 is engaged. 6A to 6D. Further, a predetermined mark may be displayed on the operation dial 31 or the exhaust power par 23 to indicate the rotation position of the operation dial 31 according to the screw size used in the screw tightening machine 1. good.

As shown in FIG. 7, an impact mechanism 5 for converting the rotational force of the air motor 4 into a high-impact rotational force is disposed below the air motor 4 housed in the housing 2. . The impact mechanism 5 includes a hammer 6 that is connected to the rotor 40 of the air motor 4 and is driven to rotate, and an anvil 7 that is hit by the rotated hammer member 6 and is driven to rotate by impact. Is done. The rotational force of the anvil 7 is transmitted to a rotary drive shaft that is engaged with a square hole formed in the center of the anvil. The hammer 6 and the anvil 7 are housed in an impact case 41 in which oil is sealed. Between the impact mechanism 5 and the air motor 4 arranged above the impact mechanism 5, an O-ring 42 for blocking compressed air supplied to the air motor 4 from entering the impact case 41 is provided. An O-ring 43 for blocking oil from leaking from inside the impact case 41 of the impact mechanism 5 and the O-ring 43 are spaced from each other. This 2 6

The two O-rings 42 and 43 are connected to the atmosphere via the exhaust passage 25 through the communication passage 44.

A cylinder 11 that houses a piston 10 formed at the lower end of the rotary drive shaft 8 is formed below the impact mechanism 5. The compressed air supplied into the cylinder 11 operates the piston 10 toward the bottom dead center of the cylinder 11. An O-ring 45 for blocking leakage of oil from inside the impact case 41 of the impact mechanism 5 and a cylinder are provided between the cylinder 11 disposed below the impact mechanism 5 and the impact mechanism 5. The O-ring 46 and the O-ring 46 that block the compressed air supplied to 1 from entering the impact case 41 are arranged at a distance. The space between the two O-rings 45 and 46 is connected to the exhaust passage 25 via a communication passage 47. That is, the space between the two O-rings 45 and 46 is connected to the atmosphere via the exhaust passage 25 and the communication passage 47.

As described above, two O-rings 42, 43 and 45, 46 are arranged at an interval between the side to which compressed air is supplied and the impact mechanism 5 filled with oil. The space between the rings 42, 43 and 45, 46 is communicated to the atmosphere via the exhaust passage 25 via the communication passages 44, 47. For this reason, even if the compressed air supplied to the air motor 4 ゃ cylinder 11 enters the impact mechanism 5 from the O-ring, the compressed air is still transmitted to the communication passages 44, 4 formed between the two O-rings. It is discharged to the exhaust passage 25 through 7. As a result, the compressed air does not enter the impact case 41 の of the impact mechanism 5. Therefore, while the impact mechanism 5 is operating, the compressed air supplied from the O-ring to the air motor 4 ゃ cylinder 11 enters the impact case 41 of the impact mechanism 5 and increases the oil pressure in the impact case 41. Therefore, it is possible to prevent the occurrence of an operation failure such as an increase in the output torque due to the operation. Also, it is possible to avoid the danger of hot oil being blown out by the pressure of the compressed air when changing the oil. Industrial applicability

As described above, according to the present invention, the compressed air exhausted from the air motor is increased. An exhaust adjustment valve configured to variably adjust a cross-sectional area of the exhaust path is provided in an exhaust path configured to exhaust air. The amount of exhaust air exhausted from the air motor is variably adjusted by the exhaust adjustment valve, and the amount of air passing through the air motor can be varied. As a result, the output torque of the air motor can be variably adjusted. Therefore, there is no need for a speed adjustment mechanism for variably adjusting the amount of compressed air supplied to the air motor. Therefore, even when the smallest screw is used, the driver bit can be driven to rotate with a torque corresponding to the screw, and no cam-out occurs. Further, since the exhaust air corresponding to the output tonnolek of the exhaust motor is exhausted to the atmosphere through the silencer, a decrease in the output of the air motor and a decrease in the silencing performance of the silencer can be prevented.

Claims

The scope of the claims

1. a screwdriver bit that engages the head of the screw and rotates the screw;

An air motor driven by compressed air pressure to rotationally drive the driver bit;

A piston coupled to the dry bit and slidably housed in a cylinder to drive the driver bit in a screwing direction by introducing compressed air into the cylinder;

An exhaust path for exhausting compressed air exhausted from the air motor,

An exhaust adjustment valve provided in the exhaust path, variably adjusting a cross-sectional area of the exhaust path to variably adjust an amount of exhaust air discharged from the air motor;

A compressed air driven screw tightening machine.

An exhaust port provided in the exhaust path, for discharging exhaust gas passing through the exhaust path in the previous period to the atmosphere;

A muffler provided on the upstream side of the exhaust port to muffle exhaust sound,

The exhaust adjustment valve is provided downstream of the air motor and upstream of the muffler.

The compressed-air-driven screwdriver according to claim 1.

3. The exhaust path has a cylindrical valve chamber,

The exhaust adjustment valve includes a plate-shaped valve body that is rotatably provided in the cylindrical valve chamber and that adjusts an amount of compressed air flowing through an exhaust path according to a rotation angle.

The compressed-air-driven screwdriver according to claim 1.

4. The plate-shaped valve is rotated to a position that completely blocks the exhaust path Sometimes has openings to ensure a minimum cross-sectional area in the exhaust path,

4. The compressed air driven screw tightening machine according to claim 3.

5. The compressed air-driven screwdriver according to claim 3, further comprising: an operation dial for rotating the plate-shaped valve element.