JPH0115477Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a device that can perform screw tightening at high speed and low torque at the beginning of tightening, and at low speed and high torque at the end of tightening.

Conventionally, electric screwdrivers or air screwdrivers have been used for screw tightening work on electrical product assembly lines.

Electric screwdrivers are noiseless, the torque can be easily adjusted, and unlike air screwdrivers, they do not pollute the environment with oil mist in the exhaust.

However, tightening large diameter screws such as M5 and M6 tapping screws requires a large torque, and the deceleration required to generate the large torque lowers the rotation speed, making it impractical.

Therefore, for large-diameter screws, air drivers, especially impact wrenches that generate large torque through a hammering effect, are often used, but this poses a noise problem.

The technical problem to be solved by the present invention is that even when the rotational drive source is an electric motor, it is possible to generate high torque while hardly reducing the screw tightening speed.

Another technical problem of the present invention is to make the device as compact as possible and to enable screw tightening in a narrow space on an assembly line.

In order to solve the above-mentioned technical problem, the present invention connects a screw tightening shaft to a drive shaft that can be rotated in forward and backward directions via a first one-way clutch, and connects the screw tightening shaft to the drive shaft in the direction of rotation transmission of the first one-way clutch. The second one-way clutch is connected to the drive shaft through a second one-way clutch that can transmit rotation in the same direction as the drive shaft, and a gear reduction mechanism that rotates in the opposite direction to the rotation direction of the drive shaft.

The first and second clutches 3, 3a are arranged coaxially, and each clutch 3, 3a alternately has relief grooves 38 and inclined pressing surfaces 34 in the axial direction of the inner surface of the drive cylinders 31, 31a into which the tightening shaft 4 is fitted. A rod-shaped roller 32 is arranged between the tightening shaft 4 and the driving cylinders 31, 31a.

The forward rotation of the drive shaft is transmitted to the screwed shaft without being decelerated by the first one-way clutch,
Tighten the screw that fits into the engagement part at the tip of the screw shaft at high speed.

When the screw is fully tightened, the drive shaft is rotated in the opposite direction, and this rotation is decelerated by the gear reduction mechanism and transmitted to the second one-way clutch, causing the screw tightening shaft to rotate at a low speed. This allows the screw to be tightened with high torque.

While either one-way clutch is engaged, the other one-way clutch is idle, and there is no problem in switching the rotational speed of the screw tightening shaft.

If an electric motor is used as the rotational power source for the drive shaft,
It does not make any noise, and unlike air drivers, it does not pollute the environment with oil mist in the exhaust.

Further, since the rotation of the screw tightening shaft when the screw is fully tightened is only reduced, the decrease in screw tightening speed is small and does not pose a problem.

The first and second clutches 3, 3a are arranged coaxially, and both clutches 3, 3a are driven by 31, 3a.
Since rod-shaped rollers are interposed between 1a and the shaft 4, the diameter of the clutch can be made much smaller than a clutch using balls instead of rollers for the same load capacity.

Therefore, the entire device can be constructed compactly, and screw tightening can be carried out without any problem in a narrow place on the assembly line.

The present invention will be specifically described below based on embodiments shown in the drawings.

A drive shaft 2 is connected to an electric motor 1 which is a rotational drive source via a coupling 11, and a screw tightening shaft 4 is connected to the drive shaft 2 via a first one-way clutch 3.
are connected.

The portion from the distal end of the motor 1 to the proximal end of the screw shaft 4 is supported by a U-shaped support member 7, and when the support member is raised and lowered by the cylinder 5, the motor 1 and the screw shaft 4 are also integrated with the support member 7. go up and down.

The first one-way clutch 3 includes a drive cylinder 31 protruding from the lower end of the drive shaft 2 and the cylinder 3, as shown in FIGS. 2 and 4.
A plurality of rollers 32 are arranged at equal intervals between the upper end of the screw tightening shaft 4 fitted in the drive tube 31, and relief grooves 38 of the rollers 32 and inclined pressing surfaces 34 for the rollers 32 are arranged alternately on the inner surface of the drive cylinder 31. If the drive shaft 2 rotates in the forward direction (clockwise rotation in FIG. 4), the rotation will be transmitted to the screw tightening shaft 4, but if the drive shaft 2 rotates in the opposite direction, the rotation will be transmitted to the screw tightening shaft 4. Also, rotation is not transmitted to the screw tightening shaft 4.

A second one-way clutch 3a similar to the first one-way clutch 3a is attached to a screw tightening shaft 4 below the first one-way clutch 3.

Tooth surfaces 20 and 30 are formed on the outer circumference of the drive cylinder 31a of the second one-way clutch 3a and the outer circumference of the drive shaft 2, and an idle gear 61 is formed on the tooth surface 20 of the drive shaft 2.
are meshing.

The idle gear 61 and the tooth surface 30 of the drive cylinder 31a are connected by a gear shaft 62. The idle gear 61 and the gear shaft 62 are pivotally fixed to the support member 7, and the tooth surface 63 at the upper end of the gear shaft 62 that meshes with the idle gear 61 has a larger diameter than the tooth surface 20 of the drive shaft 2. The tooth surface 64 of the drive cylinder 31a
It has a smaller diameter than the tooth surface 30 of.

The screw fastening shaft 4 has a screw engaging portion 41 recessed at its tip. A pipe 8 for screw suction is fitted on the outer periphery of the screw tightening shaft 4, and a suction hose 8 is attached to the pipe 8.
1 are connected.

In the drawings, reference numeral 33 denotes a bearing fitted between each drive cylinder 31, 31a of the one-way clutch 3, 3a and the screw tightening shaft 4.

FIG. 6 is a graph showing the relationship between the torque required to tighten a tapping screw and the rotation of the screw. At the beginning of tightening, the torque is low enough to allow the tapping screw to bite into the mating member. When the screw head hits the mating member, the torque increases rapidly and reaches the tightening torque within less than one rotation.

When tightening a screw, when the drive shaft 2 is rotated clockwise, the screw tightening shaft 4 rotates at high speed via the first one-way clutch 3, as shown by the arrow in FIG. 1, and the screw 9 is tightened at high speed.

The rotation of the drive shaft 2 is controlled by the idle gear 61 and the gear shaft 6.
2 to the drive cylinder 31 of the second one-way clutch 3a.
a, the cylinder 31a is rotated counterclockwise as shown in FIG.
8 and separates from the screw fastening shaft 4, allowing the screw fastening shaft 4 to rotate freely.

In the end, the drive cylinder 31a of the second one-way clutch 3a
rotates idly in the counterclockwise direction, and there is no problem with high-speed rotation of the screw tightening shaft 4 in the clockwise direction.

Just before tightening the screw, if the rotation of the motor is switched and the drive shaft 2 is rotated in the opposite direction, the second one-way clutch 3a is rotated clockwise via the idle gear 61 and gear shaft 62, as shown by the arrow in FIG. rotational force is transmitted, and as shown in FIG.
The clockwise rotation of 1a is transmitted to the screw tightening shaft 4.

The drive cylinder 31 of the first one-way clutch 3, which is directly connected to the drive shaft 2, rotates idly in the counterclockwise direction, and there is no problem in clockwise rotation of the screw tightening shaft 4.

The input to the second one-way clutch 3a is decelerated by the gear reduction mechanism 6, so the screw tightening torque is large and the screw can be strongly tightened.

Incidentally, if the switching between forward and reverse rotation of the motor is automatically performed using a timer according to the length of the mating screw, there will be no mistake in the timing of the switching.

[Brief explanation of the drawing]

Figure 1 is a front view of the screw tightening device, Figure 2 is a sectional view of the main part, Figure 3 is a side view of the main part, Figure 4 a and b are explanatory diagrams of the one-way clutch, and Figure 5 is high torque output. FIG. 6 is a graph showing the relationship between tightening torque and screw rotation. 2... Drive shaft, 3... First one-way clutch, 4
...Screw tightening shaft, 6...Gear reduction mechanism.

Claims (1)

[Claims for Utility Model Registration] A motor 1 capable of switching forward and reverse rotation, a drive shaft 2 of this motor 1, and a screw disposed coaxially below this drive shaft 2 and having a threaded engagement portion 41 at its tip. a tightening shaft 4; a first one-way rotating clutch 3 disposed on the outer circumferential surface of the proximal end of the screw tightening shaft 4; and a first one-way rotating clutch 3 disposed below the first one-way rotating clutch 3 on the outer circumferential surface of the proximal end. a second one-way rotary clutch 3a which is arranged and capable of transmitting rotation in the same direction as the first one-way rotary clutch 3; The first one-way rotation clutch 3 includes a U-shaped support member 7 that supports the base end of the shaft 4, and a gear reduction mechanism 6 disposed within the U-shaped portion of the support member 7. The second one-way rotary clutch 3a is directly connected to the drive shaft 2 and drives the screw tightening shaft 4 by the rotation of the drive shaft 2, and the second one-way rotary clutch 3a engages with the drive shaft 2 and controls the rotation of the drive shaft 2. the gear reduction mechanism 6 that rotates at a reduced speed in a direction opposite to the direction;
The clutches 3, 3a are engaged with each other to drive the screw tightening shaft 4 at a reduced speed, and each of the clutches 3, 3a has an escape groove 38 extending in the axial direction and a slope on the inner surface of the respective drive cylinders 31, 31a into which the screw tightening shaft 4 is fitted. Pressing surfaces 34 are formed alternately in the circumferential direction, and rod-shaped rollers 32 are arranged in each of the relief grooves 38, and the gear reduction mechanism 6 is pivoted on the support member 7 in parallel to the drive shaft 2. The second one-way rotary clutch 3 is provided with tooth surfaces 63 and 64 at the upper and lower ends to transfer the driving force from the drive shaft 2 to the second one-way rotary clutch 3 axially downward.
A small screw tightening device equipped with a gear shaft 62 for transmitting data to a.