JPH06289B2 - Automatic screw tightener control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is configured to eliminate the influence of inertia of a driver bit at the time of completion of screw tightening and securely perform screw tightening with a desired screw tightening torque. The present invention relates to a control device for an automatic screw tightener.

[Prior Art] Recently, there has been developed an automatic screw tightening machine configured to eliminate the influence of inertia of a driver bit at the time of completion of screw tightening and securely perform screw tightening with a desired screw tightening torque. This automatic screw tightener has a motor 2 fixed to one end of a driver body 1 as shown in FIGS. 3 and 4, and the motor may be AC or DC. Any of a brushless motor may be used. An input disc 4 forming a part of the differential planetary gear mechanism 3 is arranged in the motor 2 so as to rotate integrally with the motor 2 in response to the rotation thereof. A plurality of planetary cones 5 are arranged on the outer circumference of the input disc 4, and circumferential grooves 5a of the planetary cones 5 are frictionally engaged with the input disc 4 to rotate. A cam disk 6 that rotates concentrically with the input disk 4 is disposed on the flat surface 5b located on the back surface of the conical surface 5c of the planet cone 5 so as to frictionally engage with the input disk 4. Moreover, this cam disc 6
The driver bit 8 is connected to the driver so as to rotate integrally therewith, and the rotation of the motor 2 is transmitted to the driver bit 8.

Further, a transmission ring 7 is arranged on the outer periphery of the planetary cone 5 so as to rotate by frictionally engaging with the conical surface 5c thereof, and the transmission ring 7 is supported by an arm 9 rotatably held at one end thereof. It is rotatably held. Moreover, the speed change ring 7 is biased by the spring 10 so that its frictional engagement position is located on the high speed side, and the elastic force holding member composed of the spring 10 and the arm 9 causes the speed change ring 7 to be frictionally engaged. The position is regulated, and the maximum value of the reduction ratio and the tightening torque are determined. Further, the differential planetary mechanism 3 is immersed in the lubricating oil in the driver body 1,
The friction between the parts is reduced.

[Problems to be Solved by the Invention] In this automatic screw tightening machine, the speed change ring is generated by the reaction torque generated according to the tightening torque applied to the driver bit 8.
7 rotates. The amount of movement of the speed change ring 7 in the axial direction due to the rotation is regulated by the spring 10. Therefore, the pressing force applied to the spring 10 on the speed change ring 7 by the reaction torque and the spring 1
The transmission ring 7 moves to a position where the elastic force generated by the bending of 0 is balanced. When the load on the driver bit 8 increases, the speed change ring 7 further gradually moves to the edge of the planet cone 5, the driver bit 8 is decelerated to zero rotation, and the screw moves as shown in the characteristic curve of FIG. Tightening is done. At this time, the phenomenon that the driver bit stops rotating even though the motor 2 is still rotating at high speed occurs.However, in order to stabilize the final tightening torque, the motor bit remains for a while after the driver bit is stopped. Rotation is retained. During this time, frictional heat is generated between the components of the differential planetary mechanism, the temperature of the lubricating oil that cools it rises, and the output torque of the differential planetary mechanism decreases.

The present invention is intended to eliminate the above-mentioned drawbacks.When the transmission ring of the differential planetary mechanism moves to the zero rotation position on the conical surface of the planet cone, the motor is rotated at a low speed for a predetermined time to reverse the rear motor. It is intended to provide a control device for returning the differential planetary mechanism to the original position.

[Means for Solving the Problems] In order to solve the above-described problems, the present invention solves the above problems by providing an input disc that is rotated by a motor to rotate, a planet cone that frictionally engages the outer periphery of the input disc, and a cam that frictionally engages the planet. The driver bits are connected via the disk. A speed change ring frictionally engaged with the planetary cone is arranged on the outer circumference of the planetary cone, and the speed change ring receives a reaction force by the load of the driver bit, and the elastic force retaining member receives the reaction force. . Further, the differential planetary mechanism is immersed in the lubricating oil in the driver body, and is configured so that the frictional force between the respective parts becomes small.

On the other hand, a power supply unit is connected to the motor through a switching unit that switches the speed from high speed to low speed. Also,
A means for detecting the stop of the driver bit is provided, and the stop detection means is provided with a speed switching command section for sending a low speed forward rotation command signal to the switching means for a predetermined time when receiving the stop detection output. Further, the speed switching command section sends a forward rotation voltage cutoff command signal for cutting off the forward rotation voltage from the power supply section to the switching means when a predetermined time has elapsed, and the reverse rotation voltage is supplied from the power supply section to the motor. A controller is connected to send the command signal to the switching means.

[Operation] In the above automatic screw tightener, the forward rotation voltage is supplied to the motor to rotate the motor at high speed. The rotation of the motor is transmitted to the driver bit at a reduction ratio determined by the frictional engagement position between the planet cone and the speed change ring, and the driver bit tightens the screw. When a reaction torque is applied to the transmission ring according to the load applied to the driver bit, the transmission ring moves in the axial direction while rotating. Further, when the motor continues to rotate, the speed change ring moves in its axial direction, its reduction ratio increases and finally becomes infinite, the driver bit stops, and the stop detection output is transmitted. It This stop detection output is sent to the speed switching command section, a low speed forward rotation command signal is sent to the switching means, a low voltage is supplied to the motor from the power supply section, and the motor rotates at a low speed.
At this time, frictional heat is generated between the parts of the differential planetary mechanism,
Since the motor rotates at a low speed, frictional heat is less generated than when the motor is rotating at a high speed, the temperature rise of the lubricating oil is also small, and the output torque of the differential planetary mechanism is not reduced. Can perform tightening work.

When the motor rotates at a low speed for a predetermined time, a time-up signal is transmitted from the speed switching command section and the voltage from the power supply section is cut off. After that, a reverse rotation command signal is transmitted to the switching means, and the control unit for rotating the motor in reverse rotates differentially. Therefore, the motor reversely rotates, the planetary cone and the speed change ring slightly reversely, and the frictional engagement positions of these are returned to the original position on the high speed side, and the next work can be prepared.

Embodiments Embodiments will be described below with reference to the drawings. In FIG. 1, A is a control device of the automatic screw tightening machine shown in FIG. 3, and this control device A controls a motor (a DC motor will be explained in this embodiment) 2 of the automatic screw tightening machine. Is configured. The control device A has a work starting unit 11, and the work starting unit 11 is connected to a lifting means 12. The work starting unit 11 is a latch circuit 13 of a rotation confirmation unit 23, which will be described later, via the first pulse generator 34.
a, the first and second flip-flops 14 of the speed switching command unit 14
They are connected to a and 14b, respectively, and are configured to reset their respective latch outputs and avoid malfunctions at startup. Further, the work starting unit 11 is the first
It is connected to the counter 13b of the rotation confirmation unit 13 described later via the pulse generator 34, and the set value of the setter described later is set to the counter 1
It is configured to be set to 3b. Moreover, the work starting unit 11 is connected to the normal rotation control unit 16 via the high speed mode command unit 15, and the normal rotation control unit 16 is configured to send a high speed normal rotation command signal to the switching means 17 described later. Has been done.

The normal rotation control unit 16 is connected to a low speed mode command unit 19 which operates by receiving the inverted output of the first flip-flop 14a constituting the speed switching command unit 14, and sends a low speed normal rotation command signal to the switching means 17. Is configured. Further, the normal rotation control unit 16 is configured to receive the output of a third AND circuit 30 described later and send a cutoff signal to the switching means 17 to cut off the normal rotation voltage supplied to the motor 2.

On the other hand, a power supply unit 18 is connected to the motor 2 via a switching means 17, and when the switching means 17 receives the high-speed forward rotation command signal and a low-speed forward rotation command signal described later,
The power supply unit 18 is configured to supply two kinds of high and low normal voltage to the motor 2. Further, the switching means 17 is connected to a reverse rotation control unit 21 which operates by a signal from a pulse generation unit 20 described later, and when a reverse rotation command signal is transmitted from the reverse rotation control unit 21, the power supply unit 18 It is configured to supply a reverse rotation voltage lower than the normal rotation voltage to the motor 2.

Further, the control device A may be anywhere as long as it does not hinder the lifting and lowering of the driver bit 8 of the automatic screw tightener.
It has means for detecting the stop of the driver bit 8.
This stop detecting means is a rotation detecting section arranged corresponding to the movement path of the slit disk 23 which can be raised and lowered integrally with the driver body (not shown) and which rotates integrally with the driver bit 8 and the slit at one end thereof. It comprises a rotation detecting means 22 consisting of 24 and a speed switching command section 14. The rotation detection means
The rotation detection unit 24 of 22 is configured to emit an output pulse during detection of the passage of the slit of the slit disk 23, and the output pulse is the amplifier 25 and the waveform shaping unit 2
6. The differential circuit 27 for detecting the edge of the output pulse and the first AND circuit 38 which opens the gate by the output of the first pulse generator 34 and the output signal of the high speed mode command section 15 are passed to the rotation confirmation section 13. Is configured to join.

The rotation confirmation unit 13 includes a counter 13b that sequentially subtracts the set value set in the setter 13c by the output pulse, a latch circuit 13a that temporarily holds the count end signal of the counter 13b, and its latch output, that is, a rotation confirmation signal. Second opening gate to pass the output pulse
It consists of AND circuit 29. Also, the counter 13b
Can count while the output pulse is being output from the second pulse generating section 40 which operates according to the output signal of the high speed mode command section 15, and is in a reset state when the output pulse is not output from the second pulse generating section 40. Is configured. The predetermined pulse width of the second pulse generator 40 is set to be slightly larger than the total pulse width of the number of pulses of the set value set in the setter 13c.

The output of the latch circuit 13a is connected through an inverter, and the output of the second AND circuit 29 and the output of the time resetting means 39 described later are directly connected to the first OR circuit 32 forming a part of the speed switching command section 14. Has been done.

The speed switching command unit 14 includes the first OR circuit 32, a timer 14c which is an example of a pulse width detector, and the second AND circuit 2.
A first delay circuit 35 for receiving the output signal of 9 and the output signal of the time resetting means 39 via the second OR circuit 33 and delaying them to set the timer time set in the switching unit 14d in the timer 14c, First flip-flop 14a forming an example of a memory device
And a second AND circuit 30 which opens the gate by receiving the output of the first flip-flop 14a and the output of the second flip-flop 14b, and the second flip-flop 14b connected through the second delay circuit 36. Further, the timer 14c has a switching unit 14d for switching a set time,
When the output of the flip-flop 14a is received, the set time of the timer 14c is switched from the first time Ta to the second time Tb. This timer 14c is reset by the output pulse from the rotation detecting section 245 when the rotation confirming signal is transmitted from the latch circuit 13a of the rotation confirming section 13, and at the same time, only a slight time elapses determined by the first delay circuit 35. After that, the first time Ta set in the switching unit 14d is set immediately. Also, this timer 14
c is a time-up signal which is generated when the next output pulse is not transmitted from the rotation detecting unit 24 even if a time is set and a predetermined time Ta has elapsed, and then this is sent to the first and second flip-flops.
It is configured to output to 14a and 14b. Further, the first flip-flop 14a has a first time of the timer 14c.
Upon receiving the Ta time-up signal, the output is inverted and the low-speed mode command section 19 is operated. Further, the first flip-flop 14a has the first OR circuit 32 and the second OR circuit 33 via the time resetting means 39.
And resets the timer 14c, and then sets the second time Tb set in the switching unit 14d.

Moreover, the first flip-flop 14a is connected to the timer 14c.
In response to the time-up signal of the first time Ta, the output signal is sent to the third AND circuit 30, the gate of the third AND circuit 30 is opened, and the second flip-flop is passed through the second delay circuit 36.
It is configured to wait for the time-up signal of the second time Tb from 14b. The delay time T2 of the second delay circuit 36 is
The output of the first flip-flop 14a drives the switching unit 14d for the second time.
After switching to Tb, the timer 14c is reset and set by the time resetting means 39, and is set longer than the time until the time-up signal is output. The signal is configured so that the second flip-flop 14b does not operate.

The output signal of the third AND circuit 30 of the speed switching command unit 14 is supplied to the normal rotation control unit 16 so that the normal rotation voltage to the motor 2 supplied by the output signal from the work start unit 11 is cut off. It is configured. Also, this third AND circuit
The output signal of 30 is supplied to the third delay circuit 37, delayed by the time (T3) required for stopping the motor 2 which is normally rotating, and then, by the time-up signal of the second time Tb of the timer 14c. It is configured to be sent to the fourth AND circuit 31 which opens the gate. Further, the output of the fourth AND circuit 31 is configured to be supplied to the pulse generating section 20, and when the pulse generating section 20 receives the output signal of the fourth AND circuit 31, the reverse controlling section 21 receives the output signal. The reverse rotation command signal is transmitted to the switching means 17 by transmitting the pulse signal of the desired reverse rotation time T, and the reverse rotation voltage is supplied from the power supply unit 18 to the motor 2 for a predetermined time. Also, the pulse generator
Reference numeral 20 is configured to actuate the raising / lowering means 12 of the driver bit 8 via the machine cycle completion detecting section 38 to raise and restore the driver bit 8.

In the control device for the automatic screw tightening machine, as shown in FIGS. 2A and 2B, the elevating means 12 is activated by the output signal of the work starting section 11 and the driver bit 8 is lowered. At the same time, the output signal of the work starting section 11 is supplied to the switching means 17 via the high speed mode command section 15 and the normal rotation control section 16, and the normal voltage x is supplied from the power supply section 18 to the motor as shown in FIG. 2c. Supplied to 2. A differential planetary mechanism (not shown) including an input disc (not shown), a planet cone (not shown), a cam disk (not shown), and a speed change ring (not shown) as the motor 2 rotates. The driver bit 8 rotates via and the screw tightening starts.

Since the slit disk 23 rotates as the motor 2 rotates, an output pulse is transmitted from the rotation detection unit 24. The output pulse is waveform-shaped as shown in FIG. 2d and then sent to the counter 13b of the rotation confirmation unit 13. When the output pulse is measured by the set number set in the setter 13c within the time determined by the second pulse generator 40, the count end signal is temporarily held in the latch circuit 13a. The output signal of the latch circuit 13a is used as the rotation confirmation signal for the second
Since it is sent to the AND circuit 29, its gate is opened, and subsequent output pulses are supplied to the speed switching command section 14. Timer
If this output pulse is continuously supplied before 14c counts the first time Ta set by the switching unit 14d, the next output pulse resets the timer 14c, and the timer 14c sets the time. Do not send up signal. Also, the timer 14c is set immediately after reset,
Prepare for the next output pulse. In this state, the screw tightening progresses, the transmission ring rotates according to the load applied to the driver bit 8, its reduction ratio continuously increases, and finally the reduction ratio becomes infinite. Stops rotating. When the rotation of the driver bit 8 is stopped, the output pulse from the rotation detection unit 24 is not transmitted and the timer 14
c time-counts the first time Ta as shown in FIG. 2e, and issues a time-up signal. Therefore, as shown in FIG. 2f, the output of the first flip-flop 14a is inverted, and this inverted output operates the low speed mode command section 19, the normal rotation control section 16 and the switching means 17, and the power supply section 18 drives the motor. Supply low voltage to 2 and rotate motor 2 at low speed. Therefore, the frictional heat generated between the components of the operating planetary mechanism 3 is reduced, and the temperature rise of the lubricating oil is also reduced.

At the same time, the inverted output of the first flip-flop 14a activates the switching unit 14d of the timer 14c to switch the set time of the timer 14c to the second time Tb.

On the other hand, the inverted output of the first flip-flop 14a is the third
The second flip-flop 14b also receives the time-up signal of the timer 14c via the second delay circuit 36 as shown in FIG.
Since the timer 14c is reset by the time resetting means 39 until the output signal is input to the second flip-flop 14b by 36, and the second time Tb set in the switching unit 14d is set in the timer 14c, When the output of the first flip-flop 14a is inverted, the gate of the third AND circuit 30 is closed, and the output signal is not transmitted from the third AND circuit 30.

When the timer 14c counts the second time Tb as shown in FIG. 2e and issues a time-up signal, the second flip-flop 14b is inverted as shown in FIG. After passing through the 3 AND circuit 30, the speed switching command unit 14
As the output of the normal rotation control unit 16 to cut off the normal rotation voltage,
Motor 2 stops. At the same time, the inverted output is supplied to the third delay circuit 37, delayed by the time (T4) required to normally stop the motor 2 as shown in FIG. 2h, and pulsed via the fourth AND circuit 31. It is supplied to the generator 20.

The pulse generator 20 transmits a pulse signal having a predetermined time width T as shown in FIG. 2i and supplies it to the reverse rotation controller 21. The reverse rotation control unit 21 sends a reverse rotation instruction signal to the switching means 17 while the pulse signal is transmitted, and the power supply unit 18
The reverse rotation voltage y lower than the forward rotation voltage x is supplied to the motor 2. The motor 2 slightly rotates in the reverse direction and stops, but with the reverse rotation of the motor 2, the planet cone and the speed change ring reversely rotate. Therefore, the friction engagement position between the planetary cone and the speed change ring returns to the original position on the high speed side according to the load in the reverse rotation direction related to the driver bit 8, and the speed change ring, the cam disk and the planetary cone are locked from the motor 2 side. It will be canceled.
Moreover, the reverse rotation voltage y is the forward rotation voltage as shown in FIG. 2c.
Since it is sufficiently smaller than x, even if the reverse rotation time of the motor 2 becomes long, the driver bit 8 receives a load in the reverse rotation direction. However, this load is small, and the screw tightened by loosening the driver bit 8 in reverse. There is no such thing.

The pulse signal from the pulse generator 20 is supplied to the machine cycle completion detector 38, and its output signal is shown in FIG.
As shown in j, it is supplied to the elevating means 12, which is operated to elevate the driver bit 8 to prepare for the next work.

As described above, according to the present invention, the rotation of the motor is transmitted to the driver bit through the actuating planetary mechanism including the input disc, the planet cone, the cam disk, and the speed change ring, and the axial direction of the speed change ring. Is controlled by the elastic holding member, and when the speed change ring reaches the zero rotation position on the conical surface of the planet cone, the motor is configured to rotate at a low speed, so the speed change ring is at the zero rotation position. The frictional heat generated at times can be reduced, the temperature rise of the lubricating oil of the differential planetary mechanism can be suppressed, and the accurate tightening according to the predetermined tightening characteristics can be achieved without the output of the differential planetary mechanism decreasing. Can be performed. Note that the present invention is not limited to the above configuration, and can be similarly configured by using a microcomputer.

[Brief description of drawings]

1 is a block diagram of the present invention, FIG. 2 is a time chart of FIG. 1, FIG. 3 is an overall explanatory view of an automatic screw tightener according to the present invention, and FIG. 4 is an automatic screw tightener of FIG. FIG. 5 is a sectional view of a main part of FIG. 5, and is a torque-rotational speed characteristic curve diagram of the output shaft of the differential planetary gear mechanism according to the present invention. A control device, 1 driver body, 2 motor, 3 differential planetary mechanism, 4 input disk, 5 planetary cone, 5a circumferential groove, 5b flat surface, 5c conical surface, 6 cam disk, 7 speed change ring, 8 driver bit , 9 arms, 10 springs, 11 work starting part, 12 lifting means, 13 rotation confirmation part, 13a latch circuit, 13b counter, 13c setting device, 14 speed switching command part, 14a first flip-flop, 14b second flip-flop, 14c timer, 14d switching unit, 15 high speed mode command unit, 16 forward rotation control unit, 17 switching unit, 18 power supply unit, 19 low speed mode command unit, 20 pulse generation unit, 21 reverse rotation control unit, 22 rotation detection unit, 23 Slit disk, 24 Rotation detection unit, 25 Amplifier 26 Waveform shaping unit, 27 Differentiation circuit, 28 1st a Circuit, 29 2nd AND circuit, 30 3rd AND circuit, 31 4th AND circuit, 32 1st OR circuit, 33 2nd OR circuit, 34 1st pulse generating section, 35 1st delay circuit, 36 2nd delay Circuit, 37 third delay circuit, 38 machine cycle completion detecting section, 39 hour resetting means, 40 second pulse generating section,

Claims (1)

[Claims] 1. A motor 2 is fixed to one end of a driver body 1,
A driver bit 8 is connected to the motor 2 through an input disc 4 which rotates upon receipt of the rotation thereof, a planet cone 5 frictionally engaged with the outer periphery of the motor 2, and a cam disk 6 frictionally engaged with the disc 5, and the planet cone. A transmission ring 7 that is frictionally engaged with the outer periphery of 5 is arranged so that the reaction force applied to the transmission ring 7 by the load torque related to the driver bit 8 is received by the elastic holding member, while the input disc 4 and the planet cone Five,
Differential planetary mechanism 3 consisting of cam disk 6 and transmission ring 7
In an automatic screw tightener in which is immersed in lubricating oil in the driver body 1, the power supply unit 18 is connected to the motor 2 via the switching means 17 that switches the speed from high speed to low speed, while the stop of the driver bit 8 is detected. And a speed switching command section for sending a low speed forward rotation command signal to the switching means 17 for a predetermined time when the stop detection output of the stop detection means is received.
14 is provided, and the power supply unit 18 is further provided after the predetermined time passes.
A forward rotation voltage cutoff command signal for cutting off the forward rotation voltage from the motor 2 is transmitted from the power supply unit 18 to the switching means 17 to supply the reverse rotation voltage.
A control device comprising a control section for sending a reverse rotation voltage command signal supplied to the switching means (17).