JP2000094359A - Driving depth control mechanism in pneumatic screw driving machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving depth control mechanism in a pneumatic screw driving machine, capable of setting the driving amount of a driving screw constant regardless of the thickness of an upper material of a driven material. SOLUTION: In a pneumatic screw driving machine for tightening a driving screw 27 by a screw tightening mechanism after hammering the driving screw 27 by a hammering mechanism to such an extent that a head part of the driving screw is floated, a bumper 17 for stopping a hammering piston 3 by being brought into contact with the lower surface of the hammering piston 3 is arranged on the lower part of a hammering cylinder 2, the bumper 17 is energized by a spring so as to be positioned a little above the lower end of the hammering cylinder 2, and the hammering piston 3 driven in hammering is stopped by the bumper 17. In screwing, the hammering piston 3 is downward moved against spring force of a spring 16 by compressed air supplied in the hammering cylinder 2 by the screwing stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving depth control mechanism for a pneumatic screw driving machine for controlling the driving depth of a driving screw by a driver bit for a pneumatic screw driving machine.

[0002]

2. Description of the Related Art In general, a pneumatic screw driving machine is a device in which a driving screw is lightly driven into a material to be driven and then firmly tightened. And a screw tightening mechanism for rotating the driving screw. The striking mechanism integrally connects a driver bit to a striking piston housed slidably in the striking cylinder, operates a main valve by operating a trigger, and moves an air chamber that stores compressed air to the striking cylinder. It opens and closes and supplies compressed air to the striking cylinder to drive the striking piston. Conventionally, however, the supply amount of compressed air is always constant, and therefore, the driving force of 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 halfway into the lower material.

[0003]

However, if the driving energy is set so that the driving screw can be driven down to the lower material when the upper material constituting the material to be driven is thick, for example, the driving force is reduced when the upper material is thin. The screw may be driven too deeply into the base material, resulting in inadequate screw tightening and loss of retention.

The present invention solves the above-mentioned drawbacks, and makes the moving amount of the striking piston mechanically constant at the time of striking. It is an object of the present invention to provide a driving depth control mechanism of a striking piston in a pneumatic screw driving machine which can be constant regardless of the driving force.

[0005]

In order to solve the above-mentioned problems, a driving depth control mechanism of a striking piston in a pneumatic screw driving machine according to the present invention is provided with a compressed air from an air chamber for storing compressed air into a striking cylinder. And a screwing mechanism for driving a driver bit integrally coupled to a striking piston inside the driving bit downwardly, and a screw tightening mechanism for screwing the driver bit into a screw. In a pneumatic screw driving machine in which the screw is hit and the head of the driving screw is lifted against the material to be driven and then the driving screw is tightened by the screw tightening mechanism, the lower part of the hitting cylinder is driven. A bumper for stopping by contacting the lower surface of the operated impact piston is provided, and the bumper is connected to the air chip. The compression piston is urged to be located slightly above the lower end of the impact cylinder by the compressed air from the damper, and the impact piston driven at the time of the impact is stopped by the bumper. And the striking piston can be further moved downward by the screw tightening stroke.

[0006]

FIG. 1 shows a main part of a screw driving machine. A body 1 of the screw driving machine is provided with a striking mechanism and a screw tightening mechanism. The striking mechanism has a striking cylinder 2, a striking piston 3 slidably provided in the striking cylinder 2, and a driver bit 4 integrally connected to the striking piston 3. A main valve 7 is opened by a trigger valve 6 to be operated, and compressed air is supplied into an impact cylinder 2 from an air chamber 8 (connected to an air supply source) for storing compressed air to drive a driver bit 4 into operation. It is. Further, the screw tightening mechanism transmits the rotational force of the air motor 9 to the intermediate gear 10 and the driving gear 11, and the driving gear 1
A screwdriver is rotated by rotating a driver bit 4 (polygonal section) fitted into the center hole (polygonal shape) of the screwdriver 1 and operates almost simultaneously with the start of the operation of the striking mechanism. By rotating around the axis, the driving screw driven by the driver bit 4 is tightened.

After the driver bit 4 hits the driving screw by the above-mentioned hitting mechanism and hits the head of the driving screw so that the head of the driving screw floats on the material to be driven, the screw driving mechanism tightens the driving screw. The basic concept of such a striking mechanism and a screw tightening mechanism is described in, for example,
It is publicly known as known from JP-A-141571, JP-A-9-29037 and the like.

Next, the screw driving machine is provided with a mechanism for controlling the driving depth by controlling the moving amount of the striking piston 3. That is, the bumper stopper 12 is disposed below the impact cylinder 2. This bumper stopper 12 has a bumper receiving portion 13 on its upper part,
The lower portion is formed with a cylindrical portion 14 for slidingly guiding the driver bit 4, and is disposed slidably up and down in a cylinder lower portion 15 formed at the lower portion of the striking cylinder 2. 2 is biased to be located slightly above the lower end. The bumper receiving portion 13 is provided with a bumper 17 that is brought into contact with the lower surface of the striking piston 3 that has been driven to stop.

A cylinder lower chamber 18 is formed between the cylinder lower section 15 and the bumper stopper 12. The cylinder lower chamber 18 and the air chamber 8 are connected to the first air passage 1.
The switching valve 20 is disposed in the middle of the first air passage 19a. An exhaust port 22 is provided below the valve cylinder of the switching valve 20.
Is formed at a lower end thereof, and a second air 19b connected to a blowback chamber 21 formed around the impact cylinder 2 is formed. Thereby, usually the spring 23
1, the valve stem 24 is held at a position where the first air passage 19a is opened as shown in FIG. 1. However, the compressed air is supplied from the blowback chamber 21 to the second air passage 19b so that the valve stem 24 is opened. When it rises, the first air passage 19a is configured to close. When the first air passage 19a is closed, the cylinder lower chamber 1
Numeral 8 communicates with the exhaust port 22 from the middle of the first air passage 19a and is opened to the atmosphere.

The blowback chamber 21 communicates with the striking cylinder 2 through an air hole 25 which is opened when the bumper stopper 21 is moved downward. In a chamber where air is compressed and compressed air is supplied from the air hole 25, when the compressed air for impact is exhausted from above the impact cylinder 2, the compressed air for impact is sent from the hole again into the impact cylinder 2 and the impact cylinder 2 is released. To return to the top dead center.

Next, the operation of the screw driving machine having the above-described structure will be described. First, as shown in FIG.
When the trigger 5 is pulled, the trigger valve 6 is operated to open the main valve 4 and the compressed air is supplied from the air chamber 8 into the striking cylinder 2, the striking piston 3
Is driven downward by the air pressure, the driver bit 4 is driven to hit, hits the driving screw 27 supplied into the nose portion 26 below the body 1 and then hits the bumper 17. At this time, the air chamber 8 is
From the first air passage 19a via the switching valve 20
Compressed air is supplied through the nip, and the spring force of the compression spring 16 is also acting, so that the bumper stopper 12 does not move downward. Therefore, the impact piston 3 is connected to the bumper 17.
And stop. The driving screw 27 is a material 28 to be driven.
Is hit with the head floating. At the time of impact, compressed air is supplied into the blowback chamber 21, and this compressed air is further sent from the second air passage 19b into the switching valve 20, and the valve stem 24 is moved upward as shown in FIG. While closing the first air passage 19a, the cylinder lower chamber 18 communicates with the exhaust port 22 and is opened to the atmosphere, so that the internal pressure of the cylinder lower chamber 18 is reduced,
The bias for holding the bumper stopper 12 at the upper position is released by the air pressure and the spring force.

A part of the compressed air at the time of impact is supplied to the air motor 9, and the rotational force of the air motor 9 is transmitted from the intermediate gear 10 to the drive gear 11 to rotate the driver bit 4. Further, at the time of impact, compressed air acts on the upper surface of the impact piston 3 and the internal pressure of the cylinder lower chamber 18 is reduced as described above, so that the impact piston 3 moves downward against the compression spring 16. Then, the driving screw 27, which is driven by the driver bit 4 with the head thereof lifted from the head to be driven 28, is tightened by a floating amount (a screw tightening stroke). Then, as shown in FIG.
Screw tightening ends when reaches the bottom dead center.

When the trigger 5 is released after the screw tightening operation is completed, the main valve 7 closes and the exhaust passage (above the main valve 7) opens, whereas the blowback chamber 21 blows through the air hole 25. Since the compressed air sent into the cylinder 2 acts on the lower surface of the striking piston 3, the striking piston 3 returns to the top dead center due to the pressure difference between the upper and lower surfaces thereof. When the pressure in the blowback chamber 21 is reduced, the valve stem 24 of the switching valve 20 is lowered again by the spring force of the spring 23 and
The compressed air in the air chamber 8 is supplied to the cylinder lower chamber 18, and the bumper 17 moves upward together with the bumper stopper 12 and is held at the top dead center.

As described above, the initial position of the bumper 17 is maintained at a fixed position (top dead center) by the compressed air and the compression spring, and the impact piston 3 always stops here. Therefore, since the moving amount of the striking piston 3 is always constant, the striking depth is always constant irrespective of the thickness of the upper member of the struck member 28. Thus, the driving screw 27 can be driven to an optimum depth, and the screw can be securely tightened after the driving. Therefore, the driving screw 27 can always be properly tightened irrespective of the thickness of the upper member of the material to be driven 28.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a pneumatic screw driving machine.

FIG. 2 is an explanatory view of an operation mode of the screw driving machine at the time of hitting.

FIG. 3 is an explanatory view of an operation mode of the screw driving machine at the time of screw tightening.

[Explanation of symbols]

 2 impact cylinder 3 impact piston 4 driver bit 8 air chamber 16 compression spring 17 bumper 27 driving screw

Continued on the front page (72) Inventor Kazuhiko Kuraguchi 6-6 Nihonbashi Hakozakicho, Chuo-ku, Tokyo Max. F-term (reference) 3C068 AA10 BB01 CC02 DD11

Claims (1)

[Claims] 1. A striking mechanism for supplying compressed air from an air chamber storing compressed air into a striking cylinder to strike a driver bit integrally coupled to a striking piston in the striking piston downward, and a screw mechanism for screwing the driver bit. A screw tightening mechanism for tightening is provided, and the driver bit hits the driving screw by the above-mentioned hitting mechanism and drives the head of the driving screw to a degree that the head of the driving screw floats against the material to be driven. In a pneumatic screw driving machine for tightening a screw, a bumper is disposed below the hitting cylinder to stop by hitting a lower surface of a hitting piston that has been driven, and the hitting cylinder is driven by compressed air from the air chamber. Biased so that it is located slightly above the lower end of the The pneumatic screw, wherein the piston is stopped by the bumper, and when the screw is tightened, the biasing of the bumper by the compressed air is released to move the striking piston further downward by the screw tightening stroke. A driving depth control mechanism for a driving machine.