JP2001088053A - Automatic screw tightening machine - Google Patents

Abstract

(57) [Problem] To provide an automatic screw tightening machine capable of preventing a phenomenon that a driver bit comes off a screw driving hole, that is, a so-called cam-out. According to the present invention, a driver bit (3) having an engagement portion engageable with a drive hole of a screw is rotatably provided under the driving of an AC servomotor (2), and a thrust acting on the driver bit (3) is detected. A possible thrust detection sensor 4 is provided, and a control device 5 for changing a driving condition of the motor 2 based on thrust data obtained by the thrust detection sensor 4 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic screw tightening machine used for tightening a screw on a work. More specifically, the present invention relates to an automatic screw tightening machine for adjusting a driving condition of a rotary driving source according to a thrust acting on a driver bit. It relates to a screw tightening machine.

[0002]

2. Description of the Related Art In recent years, high-speed, high-torque motors, such as AC servomotors, which generate a large output torque even in a high rotational speed range, have been developed due to advances in motor manufacturing technology. Due to its characteristics, such motors are also actively employed in automatic screw tightening machines for automatically tightening screws.

[0003]

However, in a so-called hand-type automatic screwing machine which is manually operated by an operator, the driver bit acts on the driver bit in accordance with the tightening state of the screw, the working posture of the operator, and the like. The thrust changes each time. For this reason, when a high-speed and high-torque motor is employed, a phenomenon that the driver bit comes off from the screw drive hole during rotation due to insufficient thrust, that is, a so-called cam-out occurs, and the driver bit and the screw drive hole are damaged. There were problems such as getting lost. Screws with large leads, such as wood screws, have a large screw-in amount per rotation, so if they are tightened at high speed, not only hand-type automatic screw tightening machines but also automatic There is also a problem that the thrust is insufficient even in the screw tightening machine, and the cam out is easily caused.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a driver bit having an engagement portion engageable with a screw drive portion is driven by a rotary drive source. The thrust detecting means is provided rotatably and capable of detecting the thrust acting on the driver bit. In this configuration, it is preferable to provide a control device that changes the drive condition of the rotary drive source based on the thrust acting on the driver bit obtained by the thrust detection means. It is preferable in terms of control that the rotary drive source in the case of having the above is an AC servomotor.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes an automatic screwdriver, which is an AC servomotor 2 which is an example of a rotary drive source.
(Hereinafter, simply referred to as a motor 2). The driver bit 3 is configured to be able to engage with a drive hole formed in the head of a screw (not shown).

The automatic screw tightening machine 1 is of a hand type which is manually operated by an operator, and an arbitrary thrust is applied to the driver bit 3 by the operator during a screw tightening operation. In order to detect the thrust acting on the driver bit 3, the automatic screw tightening machine 1 is provided with a thrust detection sensor 4 as an example of thrust detection means. As the thrust detection sensor 4, for example, a strain gauge or the like that can detect distortion of a portion where a thrust acts is used.

[0007] The thrust detection sensor 4 is electrically connected to a main controller 6 in a control device 5.
An electric signal corresponding to the thrust acting on the driver bit 3 is fed back to the main controller 6.

The main controller 6 calculates proper motor drive data based on an electric signal from the thrust detection sensor 4, that is, thrust data acting on the driver bit 3, and uses the calculated data as a motor driver 7 for driving the motor 2. Send to The motor drive data calculated at this time is constituted by the rotation speed data and the torque data of the motor 2, and the like.
These values are such that cam out does not occur even if the driver bit 3 is rotated by driving the motor 2 with the thrust at that time.

The motor driver 7 determines a current value to be supplied to the motor 2 based on the motor drive data sent from the main controller 6, and drives the motor 2 based on the current value. In response to this, the driver bit 3 rotates and tightens the screw engaged with the tip to the work.

The feedback of the thrust data by the thrust detection sensor 4 is repeated during the screw tightening operation, and in response to this, the main controller 6 and the motor driver 7
The driving condition of the motor 2 is changed. Therefore, the motor 2 can be driven under the optimum condition that does not cause a camout at any time, and the screw can be tightened by the driver bit 3 by following the thrust that changes each time depending on the tightening state of the screw, the work posture of the worker, and the like. .

In the above description, the motor drive data is calculated each time in the main controller 6, but the motor drive data corresponding to the thrust data is registered in advance in a data table, and Necessary data may be read from the inside each time.
The effect obtained in this way is the same.

[0012]

According to the automatic screw tightening machine of the present invention described above, the so-called cam-out or the like, in which the driver bit comes off from the screw driving hole during the screw tightening, does not occur.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of an automatic screw tightening machine according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Automatic screwdriver 2 AC servo motor 3 Driver bit 4 Thrust detection sensor 5 Control device 6 Main controller 7 Motor driver

Claims (3)

[Claims] A thrust detecting means capable of detecting a thrust acting on the driver bit is provided with a driver bit having an engagement portion engageable with a screw driving portion, which is rotatable under the driving of a rotary drive source. An automatic screw tightening machine characterized by being provided. 2. The automatic screw according to claim 1, further comprising a control device for changing the driving condition of the rotary drive source based on the thrust acting on the driver bit obtained by the thrust detecting means. Fastening machine. 3. The automatic screwdriver according to claim 2, wherein the rotary drive source is an AC servomotor.