JP3032783U - Semi-automatic screw tightener - Google Patents

Abstract

(57) [Abstract] (Correction) [Problem] Immediately and properly detecting when a tightening screw is seated, and based on this detection, the motor drive source is shut off to automatically stop the motor drive. After that, a control circuit that can manually tighten the tightened screw with a predetermined torque value is provided. SOLUTION: The motor 10 is provided with a drooping characteristic that reduces the rotation speed of the motor at a current value I ₀ or more equivalent to the seating of a screw to be tightened, and when the current value I ₀ continues for a prescribed time or more, It is judged that the tightening screw is seated, and the motor 10
A drive control circuit for stopping the driving force of the motor and maintaining the stopped state is provided, and when the motor 10 is stopped by the function of the drive control circuit, the power supply switch 9 to the motor is re-operated. The drive control circuit is reset and includes a control circuit that can re-drive the motor.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a semi-automatic screw tightening machine that uses electric power to tighten a screw to be tightened until it is seated, and then uses manual force to tighten the screw after seating the screw. Is.

[0002]

[Prior art]

 3 and 4 are external views of the semi-automatic screw tightening machine. The semi-automatic screw tightening machine 1 has a corner wrench 3 at the other end (tip) of a torque wrench 3 having a handle 2 attached to one end thereof. A power screw tightening mechanism (nat runner) 5 capable of rotating the drive 4 by an electric motor is fixed by a mounting screw 6.

In order to tighten a screw using this semi-automatic screw tightening machine 1, first, a switch lever 7 provided in a handle 2 is operated to be incorporated into a power screw tightening mechanism 5. The motor is driven by the power supply from the power supply (battery) to the motor installed in the power screw tightening mechanism 5, and as a result, the angular drive 4 rotates and the tightening of the tightened screw (not shown) is performed. It is twisted at high speed.

When the tightened screw to be twisted is seated, its twisting load increases rapidly, so that it becomes impossible to twist the tightened screw at the rated output of the motor. Will stop. After the motor is stopped, the handle 2 is operated to rotate the entire semi-automatic screw tightening machine 1 to manually tighten the screw until the toggle built in the torque wrench 3 operates. This completes the screw tightening with the predetermined tightening torque value.

As described above, in the screw tightening work using the semi-automatic screw tightener 1, the motor is powered at a high speed until the screw to be tightened is seated, and after the seat is seated, manual tightening is performed up to the specified tightening torque value. However, the motor is overloaded in the high torque area after the tightening screw is seated due to high-speed twisting by the motor, so if this overload condition continues for a long time, the battery will be useless. May be consumed or the motor may be burned out. Therefore, in order to prevent the motor from burning out, it is required to immediately stop the power supply to the motor after the tightening screw is seated.

[0006]

[Problems to be solved by the invention]

 However, when checking the seated position of the screw to be tightened during the screw tightening work using the conventional semi-automatic screw tightener, the operator's feeling is likely to cause misidentification. However, there are problems such as consumption of electricity and burning of the motor.

Further, at the time of fastening work by the conventional semi-automatic screw fastening machine, when the screw to be fastened is seated, the switch lever 7 is operated to stop the power supply to the motor, and then the rear handle 2 It is necessary to rotate the semi-automatic screw tightening machine 1 by the manual operation described above to perform screw fastening, and these operations are burdensome to the operator and workability is poor. .

The present invention has been made in view of such conventional problems, and it is possible to properly detect the seating time of the tightened screw when the tightened screw is twisted by the driving force of the motor. Equipped with a detector that can detect the seating of the tightened screw immediately and properly, and based on this detection, shuts off the motor drive source and automatically stops the motor drive. After that, the first object is to provide a semi-automatic screw tightening machine equipped with a control circuit capable of manually tightening a screw to be tightened with a predetermined torque value.

Further, according to the present invention, there is provided a motor drive control circuit in which a cycle operation of driving and stopping the motor is performed every one cycle when a switch lever arranged on a handle portion of a semi-automatic screw tightener is operated once. A second object is to provide a semi-automatic screw tightening machine that can improve the workability of fastening a plurality of tightened screws by the semi-automatic screw tightening machine.

[0010]

[Means for Solving the Problems]

 In order to achieve the above-mentioned first object, the first aspect of the present invention comprises a motor for twisting a screw to be tightened with electric power until it is seated, and a switch for supplying power to the motor. In a semi-automatic screw tightener that twists by hand until the specified torque value is reached after the tightening screw has been seated, the motor speed must be higher than the current value equivalent to the seating of the tightening screw. A drive control circuit that has a drooping characteristic that reduces the current, and when the current value continues for a specified time or longer, determines that the tightening screw is seated and stops the motor drive force and maintains this stopped state. It is a semi-automatic screw tightening machine equipped with.

In order to achieve the above-mentioned second object, in the second aspect, in addition to the first aspect, the operation of the drive control circuit causes the electric power supply switch to the motor to be reactivated when the motor is in the stopped state. When this is done, the drive control circuit is reset, and it is a semi-automatic screw tightener equipped with a control circuit that can re-drive the motor.

[0012]

[Embodiment of the invention]

 Hereinafter, the present invention will be described in detail based on the embodiment shown in FIGS.

FIG. 1 is a block circuit diagram for controlling the driving force of an electric motor installed in the semi-automatic screw tightening machine 1, where 8 is a battery (power source) and 9 is a power feeding switch. The power feeding switch 9 is opened and closed by operating the switch lever 7 shown in FIG.

Reference numeral 10 denotes a D.V. connected to the battery 8 via a power supply switch 9. This is a C motor, and a current transformer 11 and a power control transistor 12 are interposed in a power supply circuit of the motor 10. Reference numeral 13 is a current value setting device, 14 is a signal amplifier, 15 is a relay circuit, and 16 is a motor drive circuit connected to the power control transistor 12. Reference numeral 17 is a current detector whose input side is connected to the current transformer 11, 18 is a memory circuit connected to the output side of the current detector 17, 19 is the memory circuit 18 and the load side of the power supply switch 9. Shows a one-shot multi-circuit connected between and.

Reference numeral 20 denotes a display device that displays the drive and stop status of the motor 10. The current transformer 11, the power control transistor 12, the current value setting device 13, the signal amplifier 14, the relay circuit 15 and the motor drive circuit 16 constitute a current control loop circuit 21 having a drooping characteristic.

The configuration of the present embodiment has been described above. Next, the operation thereof will be described. First, the current value setting device 13 is operated to prevent the motor 10 from overcurling, as shown in FIG. The drooping characteristic as shown is given to the motor 10.

Therefore, when the switch lever 7 is operated to close the power feed switch 9 in order to fasten a tightening screw (not shown) to the fastened body, the motor 10 rotates, and thereby the square drive 4 rotates. Then, the tightened screw is twisted at a high speed. Twisting by the motor 10 is continued until the screw to be tightened is seated, but the seated screw causes the load current value of the motor 10 to exceed the specified value (I ₀ ).

That is, the fact that the load current value exceeds the specified value is detected by the current detector 17, and the duration of the load current exceeding the specified value (I ₀ ) is continued for a long time, for example, 1 to several seconds. If it is detected that the screw is seated, the relay circuit 15 is opened, and the power control transistor is opened to stop the driving of the motor 10. You can The stopped state of the motor 10 can be displayed on the display 20 so that the operator can visually confirm that the stopped state, that is, the tightened screw is seated.

Further, if the duration of the load current exceeding the specified value (I ₀ ) is short, for example, within 1 second, it is not judged that the tightening screw is seated, and for example, the screw thread, The screw tightening load force is determined by the dust adhering to the valleys, etc., and the screw tightening by electric power is continued.

The stopped state of the motor after the seating is stored and maintained by the storage circuit 18, so that the motor 10 is not driven after the seating.

Therefore, after the tightened screw has been seated, the screw is manually tightened to a predetermined torque value (set torque value) by manual operation of the semi-automatic screw tightening machine 1, whereby the first screw tightening is performed. Is completed.

Next, when the other tightened screw is to be tightened, the power switch 9 is once opened and then closed again to output a pulse signal from the one-shot multi-circuit 9. The pulse signal outputs the pulse signal to the memory circuit 18 Is reset, whereby the relay circuit 15 and the power control transistor 12 are restored, the re-driving of the motor 10 is started, and the fastened screw is electrically turned into a high-speed state. The subsequent screw tightening operation is performed in the same manner as the above operation.

[0023]

[Effect of the invention]

 As described above, according to the present invention, the drive circuit of the motor 10 is automatically shut off when the screw to be tightened is seated during the screw tightening by the electric force of the semi-automatic screw tightener. Without imposing a load, this can prevent burnout of the motor 10 and unnecessary consumption of the battery.

In the automatically stopped motor 10, the power supply circuit of the motor 10 is restored by touching the switch lever that opens and closes the power feeding switch 9, so that a plurality of tightening screws are continuously connected. It is possible to obtain effects such as improved workability and ease of screw tightening work.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a control circuit incorporated in a semi-automatic screw tightener of the present invention.

FIG. 2 is an explanatory diagram of a drooping characteristic given to a motor.

FIG. 3 is an external plan view of a semi-automatic screw tightener used in the present invention.

FIG. 4 is an external side view of a semi-automatic screw tightener used in the present invention.

[Explanation of symbols]

1 ... Semi-automatic screw tightener 2 ... Handle 3 ... Torque wrench 4 ... Square drive 5 ... Power screw tightening mechanism 6 ... Mounting screw 7 ... Switch lever 8 ... Battery 9 ... Feed switch 10 ... Motor 11 ... Current transformer 12 ... Electric power Controlling transistor 13 ... Current value setting device 14 ... Signal amplifier 15 ... Relay circuit 16 ... Motor drive circuit 17 ... Current detector 18 ... Memory circuit 19 ... One-shot multi-circuit 20 ... Display 21 ... Current control loop circuit

Claims (2)

[Utility model registration claims] 1. After seating of the tightened screw, the motor (10) twists the tightened screw up to its seat with electric power and a switch (9) for supplying power to the motor (10). Is a semi-automatic screw tightener that twists by hand until it reaches a specified torque value. In the motor (10), when the current value (I ₀ ) corresponding to the seating of the tightened screw is greater than When the current value of (I ₀ ) continues for a specified time or longer, it is determined that the tightening screw is seated and the driving force of the motor (10) is stopped and the stop is performed. A semi-automatic screw tightener, which is equipped with a drive control circuit for maintaining the state. 2. The operation of the drive control circuit according to claim 1,
When the motor (10) is in a stopped state, the drive control circuit is reset when the power feeding switch (9) to the motor is restarted, and a control circuit capable of redriving the motor is provided. A characteristic semi-automatic screw tightener.