JP2000218570A - Anti-vibration structure for reciprocating tools - Google Patents

Abstract

(57) [Summary] (Modifications) [Problem] To compensate for vibration generated by reciprocating motion by making the pressure receiving areas of the first and second free pistons and the mass substantially equal to each other by the mutual movements, and Reduce vibration. A first and a second free piston (8, 9) are arranged adjacent to each other in an axial direction inside a cylinder, and cylinder chambers (R1, R2, R3) are defined in the cylinder.
1, a flow path through which air can be selectively introduced into R2, R3, and when air is introduced into the middle cylinder chamber, the first,
The direction in which the first and second free pistons simultaneously approach when the second free piston moves away from each other and air is introduced into the front cylinder chamber of the second free piston and the rear cylinder chamber of the first free piston. And a reciprocating tool for machining a workpiece by reciprocating the tool holding shaft 14, wherein the first free piston and the second free piston have substantially equal masses, and a pressure receiving area on which air pressure acts. Are set equal to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration preventing structure suitable for a hand type reciprocating tool driven by compressed air.

[0002]

2. Description of the Related Art Conventionally, various types of hand-held cutting tools and grinding tools using electric power as a driving source have been proposed. The weight was increased and the handling was not satisfactory. In order to improve such a point, the present applicant has proposed a reciprocating tool using compressed air as a driving source (see Japanese Utility Model Publication No. 4-2781).

The operation of this tool will be described with reference to FIG. 2. FIG. 2 is a sectional view of the tool. In this pneumatic reciprocating tool, a cylinder 102 is inserted into a housing 101 that also serves as a grip, and an air introduction passage and an air discharge passage are formed on an inner peripheral surface of the housing 101 that contacts the outer periphery of the cylinder 102. Is formed. A first and a second free piston 105 inside the cylinder 102;
A front end of the housing 101 is supported at a front end of the housing 101 so as to freely move back and forth on a support shaft 108 of a tool 107 fixed at one end to the second free piston 106. They are closed by a member 103 and a rear end member 104 provided with a valve 109 for opening and closing the compressed air supply path by an operation lever 110. In the cylinder, front, middle and rear cylinder chambers R1 and R1 are provided by first and second free pistons.
R2 and R3 are defined, and the front cylinder chamber R1 is formed with a passage 111 formed in the second free piston during operation, and the middle cylinder chamber R2 is formed with first and second free pistons 105 and 106 during operation. Passage 11
2, 114, and further, into the rear cylinder chamber R3, through a passage 115 formed in the first free piston 105, a compressed air can be introduced through a compressed air introduction passage formed in the inner peripheral surface of the cylinder 101. When the compressed air is supplied, the first and second free pistons 105 and 106 operate in opposite directions.

Therefore, in this pneumatic reciprocating tool, compressed air is introduced into the middle cylinder chamber R2 formed between the first and second free pistons 105, 106 through the air introduction passage, and the first and second free pistons are moved. 2 free piston 105, 1
When the front cylinder chamber R1 and the rear cylinder chamber R3 formed before and after 06 communicate with the air discharge passage, both pistons 1
05 and 106 move in the direction in which they separate from each other, and simultaneously introduce compressed air into the front cylinder chamber R1 and the rear cylinder chamber R3 via communication passages 111 and 115 formed in the first and second free pistons. When the middle cylinder chamber R2 formed between the first and second free pistons communicates with the air discharge passage, both pistons 105 and 106 move in the approaching direction. At this time, the reciprocating motion of the first and second free pistons 105 and 106 and the instantaneous force generated between the two pistons cause the cutting tool and the grinding tool 107 provided on the second free piston 106 to reciprocate at high speed and stably. And work can be processed. The details of the operation of switching the passage for introducing compressed air into the front, middle, and rear cylinder chambers and exhausting compressed air from the cylinder chambers are described in the above-mentioned publications, and will not be described here.

In particular, in this tool, the first and second free pistons having substantially the same mass are moved symmetrically during the operation of the tool, that is, the movement of the first and second free pistons in the direction approaching each other. And the movement in the direction away from each other are performed simultaneously and alternately continuously), so that the reciprocating motion of the second free piston can be canceled by the reciprocating motion of the reverse action of the first free piston. Thus, vibration caused by the second free piston generated during work processing can be extremely effectively prevented.

[0006]

However, in the above-described tool, the pressure receiving area A1 on the right side of the first free piston 105 in the figure is larger than the pressure receiving area A2 on the left side of the second free piston 106. As a result, a difference occurs between the pressure receiving area A1 on the right side of the first free piston 105 in the figure and the pressure receiving area A2 on the left side of the second free piston 106 in FIG. For this reason, both free pistons 105, 10
6 move in a direction approaching each other, a difference occurs in the forces acting on both free pistons, and the reciprocating motion of the second free piston 106 is completely canceled by the reciprocating motion of the first free piston 105 acting in reverse. It was not possible to reduce the vibration value.

Therefore, the present invention provides a pressure regulating shaft having the same cross-sectional area as the integral B of the support shaft 108 provided on the second free piston on the right side of the above-mentioned conventional tool on the side of the first free piston. By providing the same, the pressure receiving area on the right side in the drawing of the first free piston and the pressure receiving area on the left side of the second free piston are made equal, and the reciprocating motion of the second free piston is completely completed by the reciprocating motion of the reverse action of the first free piston. It is an object of the present invention to solve the above-mentioned problems by proposing a new reciprocating power tool capable of canceling vibration.

According to the present invention, the first and second free pistons have substantially the same mass, and the pressure receiving area in the direction in which the first and second free pistons approach each other, and the first and second free pistons are mutually separated. Since the pressure receiving areas in the separating directions are formed to be equal to each other, the vibration generated by the reciprocating motion of the first and second free pistons is theoretically completely canceled out by the mutual movement, and the vibration of the tool is reduced. It can be suppressed reliably.

[0009]

For this reason, the technical solution adopted by the present invention is to dispose first and second free pistons adjacent to each other in the axial direction so as to be able to move back and forth inside the cylinder, By the first and second free pistons, the front, middle and rear cylinder chambers R1, R2, R3
And the front cylinder chamber R1, the middle cylinder chamber R
And a flow passage through which air from the air source can be selectively introduced into the rear cylinder chamber R3 and the first air from the air source.
When introduced into the middle cylinder chamber between the free piston and the second free piston, the first and second free pistons move away from each other, and the air from the air source is moved to the second free piston.
When the first and second free pistons are introduced into the front cylinder chamber of the free piston and the rear cylinder chamber of the first free piston, the first and second free pistons move at the same time. A reciprocating tool that reciprocates a tool holding shaft provided in front of a free piston and processes a workpiece with a tool attached to the shaft. A shaft portion having the same diameter is provided, the masses of the first free piston and the second free piston are substantially equal, and the air pressure from the air source is equal to the first pressure.
A vibration isolating structure for a reciprocating power tool, wherein the pressure receiving areas acting on the free piston and the second free piston are made equal.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A reciprocating tool according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a reciprocating tool according to the present embodiment, and FIG. A sectional view, FIG. 3 (A) is an enlarged BB sectional view in a state where the flow path of the valve is closed, (B) is an enlarged BB sectional view in a state where the flow path of the valve is opened, FIG. 4 is an enlarged CC sectional view of the valve ring and the hose nipple. Note that the left side in the figure, that is, the tool mounting side is the front, and the right side in the figure, that is, the compressed air supply side, is the rear.

In the drawing, reference numeral 1 denotes a housing, 2 denotes a rubber tube for preventing cold sensation which is attached, welded or adhered to the outer periphery of the housing 1, 3 denotes a cylinder, 4 denotes an outer periphery of the cylinder 3, and , Forming a compressed air introduction passage and an exhaust passage. On the inner peripheral surface of the partition 4, an air introduction passage 4a and an air discharge passage 4b similar to those of the conventional tool described above are formed, and a contact portion between the periphery of the air introduction passage 4a and the cylinder 3 is formed. An O-ring 5 for maintaining the airtightness of the passage is arranged in the axial direction.

A front end cap 6 is attached to the left end of the cylinder 3 in the figure, and a rear end cap 7 is attached to the right end in the figure. And the second free pistons 8 and 9 are arranged adjacent to each other in the axial direction so as to be movable back and forth, and the front, middle, and Rear cylinder chamber R1,
R2 and R3 are defined.

A distal end member 1 for abutting the outer periphery of the front end cap 6 with the end of the partition 4 and fixing the housing 1 in which the rubber tube 2 is inserted.
0 is arranged. A tool holding shaft 14 fixed to the second free piston 9 is slidably supported by a bearing 12 arranged at the center of the tip member 10 and a bearing 13 arranged at the center of the front end cap 6 slidably. The holding shaft 14 is slidable in the axial direction with respect to the tip member 10 so that it cannot rotate relative to the tip member 10.
The outer shape of the tool holding shaft 14 is formed in a rectangular shape as shown in FIG. Also, a tool fixing means 14a is provided at the tip.
Is provided. Note that the outer diameter of the tool holding shaft 14 is not limited to a square, and may be any shape as long as relative rotation can be prohibited. Further, the bearing 12 disposed on the distal end member 10 is held in a state in which the bearing 12 is prevented from rotating with respect to the distal end member 10 by the set screw 12a and is prevented from coming off by the stop ring 11. The tool holding shaft 14 has an end fitted into the center hole of the second free piston 9 and fixed to the second free piston 9 by a screw 15.

A valve 16 is rotatably fitted to the center of the rear end cap 7 on the right side in the figure, and a hose nipple 17 is integrally formed at the right end of the valve 16 in the figure. . As shown in FIG. 4, a valve ring 18 is fitted around the valve 16 so as to be relatively non-rotatable. The valve ring 18 is rotatably fitted around the outer periphery of the housing 1 and extends therefrom. Are arranged so as to contact the end of the rubber-like tube 2. Therefore, the valve ring 1
When the valve 8 is rotated, the valve 16 also rotates, so that the flow path of the valve 16 can be opened and closed.

A compressed air passage 1 is provided at the center of the valve 16.
6a is formed, and this passage 16a communicates with a pair of passages 16b formed in the centrifugal direction of the valve 16,
When the valve 16 rotates, the pair of passages 16b communicate with the compressed air introduction passage 4a formed in the partition 4 via the passage 7a formed in the rear end cap 7 (FIG. 2 (b)) or the non-communication state. (FIG. 2A). As described above, the compressed air introduction passage 4a formed in the partition 4 cooperates with the outer periphery of the cylinder 3 to form a passage, and the periphery of the passage is kept airtight by an O-ring 5.

A shaft portion 19 having substantially the same diameter as the tool holding shaft 14 is provided at the center of the rear end cap 7.
Are slidably fitted, and the shaft portion 19 is formed integrally with the center of the first free piston 8. The shaft portion 19 may be fixed to the first free piston 8 with a screw or the like. A centrifugal hole 21 is formed in the fitting portion of the shaft portion 19 of the first free piston 8, and this hole 21 communicates with an exhaust passage 4 b formed between the partition 4 and the outer periphery of the cylinder 3. I have.

Two circumferential grooves 23 and 24 are formed on the outer periphery of the first free piston 8, and the left groove in the figure is formed through a passage 25 formed in the first free piston 8 through the first free piston 8.
The groove 23 on the right side in the drawing communicates with the rear cylinder chamber R3 defined between the free piston 8 and the rear end cap 7, and the first groove 23 is formed through a passage 26 formed in the first free piston 8. It communicates with a middle cylinder chamber R2 partitioned between the free piston 8 and the second free piston 9.

When the first free piston 8 moves in the axial direction in the cylinder 3 and is aligned with the hole 27 formed in the cylinder 3, the two grooves 23 and 24 supply compressed air from the hole to the central cylinder chamber R2 or the front. The compressed air in the cylinder chamber on the other side is introduced to the atmosphere through the air discharge passage 4b. Therefore, when the first free piston 8 moves in the cylinder 3 in the axial direction and the left groove 24 of the two grooves matches the hole 27 formed in the cylinder 3 for introducing compressed air, the partition 4 and the cylinder 3 The rear cylinder chamber between the first free piston 8 and the rear end cap 7 through the hole 27, the groove 24, and the passage 25 formed in the first free piston 8 from the compressed air introduction passage 4a formed by Introduced to R3, the first free piston 8 moves to the left in the figure. At this time, the central middle cylinder chamber R2 communicates with the atmosphere through a compressed air discharge passage 4b formed by the partition 4 and the cylinder 3 through an exhaust hole (not shown).

The first free piston 8 is connected to the cylinder 3
When the groove 23 on the right side of the two grooves matches the hole 27 formed in the cylinder 3, the compressed air flows through the hole 27 from the compressed air introduction passage 4 a formed by the partition 4 and the cylinder 3. The compressed air is introduced into the passage 26 formed in the first free piston 8 through the intermediate cylinder chamber R2, while the rear cylinder chamber R3 is formed by the partition 4 and the cylinder 3 through the exhaust hole 3a. The compressed air discharge passage 4b is open to the atmosphere.

Also, on the outer periphery of the second free piston 9,
As with the first free piston 8, two circumferential grooves 28, 29
The groove 29 on the right side in the figure communicates with the front cylinder chamber R1 between the second free piston 9 and the front end cap 6 via a passage 31 formed in the second free piston 9. The groove 28 on the left side in the drawing communicates with the middle cylinder chamber R2 between the first free piston 8 and the second free piston 9 via a passage 32 formed in the second free piston 9. .

When the second free piston 9 moves in the cylinder 3 in the axial direction and is aligned with the hole 30 formed in the cylinder 3, the two grooves 28 and 29 allow compressed air to flow from the hole into the middle cylinder chamber R 2 or the front. Compressed air is introduced into the outer cylinder chamber R1, and is released from the other cylinder chamber to the atmosphere via the air discharge passage 4b. For this reason, when the second free piston 9 moves in the cylinder 3 in the axial direction and the right groove 29 of the two grooves matches the compressed air introduction hole 30 formed in the cylinder 3, the partition 4 and the cylinder 3 Compressed air flows from the formed compressed air introduction passage 4a into the holes 30 and the grooves 2.
9, introduced into the front cylinder chamber R1 between the second free piston 9 and the front end cap 6 through the passage 31 formed in the second free piston 9, and moves the second free piston rightward in the figure. I do. At this time, the central middle cylinder chamber R2 communicates with the atmosphere through the compressed air discharge passage 4b formed by the partition 4 and the cylinder 3 through the exhaust hole 3b.

The second free piston 9 is connected to the cylinder 3
When the groove 28 on the left side of the two grooves is aligned with the hole 30 formed in the cylinder 3, the partition 4
The compressed air is introduced from the compressed air introduction passage 4 a formed by the cylinder 3 and the second free piston 9 through the hole 30.
And compressed air is further introduced into the middle cylinder chamber R2, while the compressed air is introduced into the front cylinder chamber R1.
Is opened to the atmosphere from a compressed air discharge passage 4b formed by the partition 4 and the cylinder 3 through the exhaust hole 3c.

The first free piston 8 and the second free piston 9 are formed to have substantially the same mass, and the first free piston 8 and the second free piston 9 have the same pressure receiving area at the left and right ends in the drawing. I have. That is, the diameter of the tool holding shaft 14 and the shaft portion 19 are formed to have substantially the same diameter. Further, a spring 33 for urging the first free piston 8 and the second free piston 9 in a direction separating them is arranged.

The operation of the reciprocating tool will be described. By rotating the valve ring 18, the passage 16b formed in the valve 16 and the rear end cap 7 as shown in FIG.
When the compressed air communicates with the passage 7a, the compressed air enters the passage 7a formed in the rear end cap 7 from the passage 16b in the valve, passes through the hole 4a formed in the cylinder 3, and the passage formed by the outer periphery of the cylinder 3 and the partition 4. 4a. In this state, when the holes 27 and 30 formed in the cylinder 3 communicate with the grooves 24 and 29 formed in the first and second free pistons 8 and 9, the passage 25 formed in the first and second free pistons 8 and 9. , 31 flows into the front cylinder chamber R1, the rear cylinder chamber R3,
The first free piston 8 and the second free piston 9 move toward the center toward each other.

When the first free piston 8 and the second free piston 9 come to the end of the movement on the center side, the holes 27 and 30 formed in the cylinder 3 are now inserted into the first and second free pistons 8 and 9.
The compressed air is introduced into the middle cylinder chamber R2 through the passages 26 and 32 formed in the first and second free pistons 8 and 9, and the first free piston 8 The second free piston 9 moves away from each other. Then, when reaching the left and right end of movement, the compressed air is again supplied from the holes 27 and 30 formed in the cylinder 3 to the grooves 2 formed in the first free piston 8 and the second free piston 9.
4, 29, the passages 25, 31 through the front cylinder chamber R
1. Introduced into the rear cylinder chamber R3, the first free piston 8 and the second free piston 9 move toward the center.
At this time, the cylinder chamber in the direction in which each free piston moves communicates with the air discharge passage 4b, and the air in the cylinder chamber is exhausted from this exhaust passage. The operation of introducing the compressed air into the cylinder chamber and the operation of switching the flow path of the exhaust gas are the same as those of the aforementioned conventional tool.

By repeating the above operation, the first free piston 8 and the second free piston 9 reciprocate in opposite directions, and the tool holding shaft 14 attached to the second free piston 9 reciprocates in the axial direction. And the tool held by the shaft processes the workpiece. Also,
Since the first free piston 8 also reciprocates with respect to the reciprocating motion of the second free piston 9, the vibrations of both can be canceled and the vibration can be greatly reduced.

As described above, according to the present invention, the masses of the first and second free pistons 8 and 9 are made substantially the same,
Since the pressure receiving area acting in the direction in which the free pistons 8 and 9 approach each other and the pressure receiving area in the direction in which the first and second free pistons 8 and 9 are separated from each other are formed to be equal, the first and second free pistons are respectively formed. The vibration caused by the reciprocating motion of the free pistons 8 and 9 is theoretically completely canceled by the mutual movement, and the vibration of the tool can be greatly reduced.

In the above embodiment, the air introducing valve is of a rotary type, but the present invention is not limited to the rotary type, and a valve similar to a conventional valve can be used. In addition, the present invention can be embodied in other various forms without departing from the spirit or main features thereof, and the above-described embodiments are merely exemplifications in all respects, and Not be.

[0029]

As described in detail above, according to the present invention,
The first and second free pistons have the same mass, and
Since the pressure receiving area in the direction in which the first and second free pistons approach each other and the pressure receiving area in the direction in which the first and second free pistons are separated from each other are formed to be equal,
The vibration generated by the reciprocating motion of the first and second free pistons is theoretically completely canceled out by the mutual movement, and an excellent effect that the vibration of the tool can be greatly reduced can be obtained. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a reciprocating power tool according to an embodiment.

FIG. 2 is an enlarged sectional view of the tool holding shaft section taken along line AA.

FIG. 3A is an enlarged BB cross-sectional view in a state where the flow path of the valve is closed, and FIG. 3B is an enlarged BB cross-sectional view in a state where the flow path of the valve is opened.

FIG. 4 is an enlarged view C- of the valve ring and the hose nipple.
It is C sectional drawing.

FIG. 5 is a side sectional view of a conventional reciprocating tool.

[Explanation of symbols]

 Reference Signs List 1 housing 2 rubber-like tube 3 cylinder 4 partition 5 O-ring 6 front end cap 7 rear end cap 8 first free piston 9 second free piston 10 tip member 11 stop ring 12, 13 bearing 14 tool holding shaft 15 screw 16 valve 17 hose Nipple 18 Valve ring 19 Shaft part 20 Screw 21 Hole 23, 24 Groove 25, 26 Passage 27 Hole 28, 29 Groove 31, 32 Passage R1 Front cylinder chamber R2 Middle cylinder chamber R3 Rear cylinder chamber

Claims (1)

[Claims] A first and a second free piston are disposed inside a cylinder so as to be movable back and forth adjacent to each other in an axial direction, and a front, a middle and a rear are formed in the cylinder by the first and second free pistons. The cylinder chambers R1, R2, and R3 are partitioned, and a flow path through which air from an air source can be selectively introduced into the front cylinder chamber R1, the middle cylinder chamber R2, and the rear cylinder chamber R3 is formed. Is introduced into the middle cylinder chamber between the first free piston and the second free piston, the first and second free pistons move away from each other, and the air from the air source flows in front of the second free piston. When the first and second free pistons are introduced into the rear cylinder chamber and the rear cylinder chamber of the first free piston, the first and second free pistons move in the direction of approaching at the same time. A reciprocating tool that reciprocates a tool holding shaft provided in front of the second free piston to process a workpiece with a tool attached to the shaft, and that the tool is located behind the first free piston. A shaft portion having substantially the same diameter as the holding shaft is provided, and the masses of the first free piston and the second free piston are substantially equal, and
An anti-vibration structure for a reciprocating power tool, wherein an air pressure from an air source is made equal to a pressure receiving area which simultaneously acts on a first free piston and a second free piston.