JPH0724175Y2 - Automatic screw tightening device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding an automatic screw tightening device using an electric screwdriver, an electric screwdriver is moved up and down together with a main body for the purpose of shortening the time from the end of lowering the electric driver to the start of rotation. In an automatic screw tightening device for tightening a screw while lowering a screw, a movable sleeve mounted around a driver bit of the electric screwdriver, a sensor detection rod attached to the sleeve, and a tip of the sleeve are It is configured to include a spring that projects forward from the screw attracted to the tip of the driver bit, and a screw tightening start sensor that detects the displacement of the detection rod when the sleeve contacts the object to be tightened and retracts.

[Industrial application field]

The present invention relates to an automatic screw tightening device using an electric screwdriver.

A screw tightening machine that automates the process from suction of screws to tightening is convenient when the same screw tightening process is repeated for each mass-produced product.

[Conventional technology]

The XY table type screw tightener two-dimensionally positions a main body to which an electric screwdriver is attached in a horizontal plane, and tightens the screw while lowering the main body at that position. This screw tightening includes the steps of lowering the tip of the screw adsorbed on the tip of the electric screwdriver to the screw hole of the object to be tightened, rotating the electric screwdriver to tighten the screw, and raising the electric screwdriver after the screw tightening is completed. Be subdivided into The process with these is accompanied by the lowering of the main body, and the process with the latter is accompanied by the upward movement of the main body.

[Problems to be solved by the device]

In the conventional screw tightening machine, the time from the start of the descending process to the start of rotation of the driver is made constant by the timer, so if the position of the object to be fastened is low and the descending time of However, the position of the object to be fastened is high,
If the descent time is short, there is a disadvantage that useless waiting time occurs before the start of driver rotation.

The present invention detects the descent of the driver to the tightening position with a sensor, and can reduce the unnecessary waiting time until the driver starts rotating.

[Means for Solving the Problems]

The present invention relates to an automatic screw tightening device that raises and lowers an electric screwdriver together with a main body and tightens a screw while lowering the main body, and a movable sleeve (4) mounted around a driver bit (3) of the electric screwdriver. A sensor detection rod (7) attached to the sleeve, a spring (5) for projecting the tip of the sleeve forward of the screw (9) attracted to the tip of the driver bit, and the sleeve. An optical screw tightening start sensor (S1) that detects the displacement of the detection rod when it comes in contact with the tightened object and retracts, and when the screw is screwed to the tightened object (10) by the driver bit. An optical screw float detection sensor (S2) that detects the displacement of the detection rod is provided, and the detection rod that detects the start of screw tightening is the same as the detection rod that detects screw float, and also detects the screw float. Detection rod And it is characterized by comprising forming thinner than the detection rod for detecting the screw tightening start.

[Action]

The sleeve has a function of detecting the relative distance taken by the electric screwdriver that moves up and down together with the main body with respect to the object to be fastened at a fixed position. The sensor detection rod causes the screw tightening start sensor to detect a minute position change of the sleeve. The screw tightening start sensor detects from the displacement of the detection rod that the tip of the sleeve comes into contact with the object to be tightened and slightly retracts (actually, the sensor moves forward) as the main body descends. Since the tip of the sleeve protrudes from the screw attracted to the tip of the driver bit, if the tip of this sleeve contacts the object to be fastened, the driver bit is rotated and the main body is further lowered. It does not matter even if the start is started, and by doing so, useless waiting time can be omitted, and the screw tightening work can be speeded up.

In addition, cost reduction is achieved by using a common detection rod for detecting screw floating and screw tightening, and wear and mechanical destruction of the contact part are prevented because a non-contact type optical sensor is used. Lost.

Further, the detection rod for detecting the screw floating can be formed to be thinner than the detection rod for detecting the screw tightening start, so that the screw floating can be detected exactly.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. (A) is a partial cross-sectional front view, (b) is a side view of a sensor section,
(C) is an enlarged view of the sensor detection rod.

In the figure, 1 is a main body that can be moved horizontally and vertically, 2 is a motor for an electric driver attached to the main body, 3 is a driver bit that is rotationally driven by the motor, and 4 is a movable sleeve mounted around the driver bit. Reference numeral 5 is a compression coil spring that constantly presses the sleeve downward, 6 is a guide of the sleeve, 7 is a sensor detection rod attached to the cap 4 of the sleeve 4,
S1 is a screw tightening start sensor, S2 is a screw lift detection sensor, 9
Is a screw, 10 is an object to be tightened (work), and 11 is its screw hole.

When the main body 1 is in the raised position, the sleeve 4 is lowered by the spring 5 until the fall prevention portion 8 contacts the upper surface of the guide 6. In this state, the tip of the driver bit 3 is sufficiently rearward of the tip of the sleeve 4, so that the screw 9 attracted to the tip of the bit 3 also has the sleeve 4 as shown in FIG.
Hiding inside. Generally, the screw 9 is attracted by the sleeve 4
The rear end side is vacuumed.

In the state shown in FIG. 2A, the sensor detection rod 7 blocks the optical path of the sensor S1 as shown in FIG. This sensor S1 is a microphotosensor in which a light emitting element and a light receiving element are opposed to each other, and the state in which the optical path is blocked is defined as ON (the same applies to the sensor S2). When the main body 1 is lowered from this state, FIG. 3 (a)
As described above, the tip of the sleeve 4 contacts the work 10, and the detection rod 7 is disengaged upward from the optical path of the sensor S1 as shown in FIG. FIG. 3 shows a state in which the tip of the sleeve 4 comes into contact with the work 10 and then the main body 1 further descends so that the tip of the screw 9 reaches the entrance of the screw hole 11. The rotation of the motor 2 occurs immediately after the sleeve 4 contacts the work 10, that is, when the sensor S1 is turned on.
Can be started when turned off. When the main body 1 is lowered as the motor 2 rotates, the screw 9 is screwed into the screw hole 11, and eventually the head of the screw 9 comes into close contact with the work 10 as shown in FIG. In this state, the torque of the motor 2 suddenly increases, and the detection rod 7 changes the sensor S2 on the upper side.
Since it is turned on, it can be determined that screw tightening is complete. If the sensor S2 remains off even if the torque of the motor 2 rapidly increases, it can be determined that the screw 9 is in the "screw lift" state in which the screw 9 is not tightened in the normal state.

As shown in FIG. 1 (C), the detection rod 7 is formed with a large diameter portion 71 for starting screw tightening and a small diameter portion 72 for detecting screw floating, and the sensor S1 has the large diameter portion 71 and the sensor S2. Detects the small diameter portion 72. Since it is difficult for the sensor to detect the small diameter portion 72, the small diameter portion 72 is applied to the sensor S2, so that the screw lift is strictly detected. Further, the sensor S2 side can be adjusted in position in the height direction so as to absorb a difference in thickness of the head of the screw 9 and a dimensional difference due to replacement of the driver bit 3.

[Effect of device]

As described above, according to the present invention, in the automatic screw tightening device, the time from the descent to the rotation of the electric screwdriver can be shortened to the actually required time, so that it is not necessary to lengthen the working time due to unnecessary waiting time. There are advantages.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 to 4 are state diagrams showing the operation of the present invention. In the figure, 1 is a main body, 2 is a motor, 3 is a driver bit, 4
Is a sleeve, 5 is a compression coil screw, 7 is a sensor detection rod,
9 is a screw, 10 is an object to be tightened, and S1 is a screw tightening start sensor.

Claims (1)

[Scope of utility model registration request] 1. An automatic screw tightening device for raising and lowering an electric screwdriver together with a main body and tightening the screw while lowering the main body, wherein a movable sleeve (4) mounted around a driver bit (3) of the electric screwdriver. ), A sensor detection rod (7) attached to the sleeve, and a spring (5) for projecting the tip of the sleeve forward from the screw (9) attached to the tip of the driver bit.
And an optical screw tightening start sensor (S1) for detecting the displacement of the detection rod when the sleeve comes into contact with the object to be tightened and retracts.
And an optical screw float detection sensor (S2) that detects the displacement of the detection rod when the screw is fastened to the object to be fastened (10) by the driver bit, and the start of screw fastening is detected. The detection rod and the detection rod for detecting the screw float are the same, and the detection rod for detecting the screw float is formed to be thinner than the detection rod for detecting the start of screw tightening. .