JPS62173125A - Control device for automatic screw driving machine - Google Patents

Abstract

PURPOSE:To provide smooth separation from a screw at the time of rising return of a driver bit by transmitting rotation of a drive motive to the bit via a planetary gearing, restricting motion of a transmission ring and supplying inverted voltage for a certain period of time after stopping of voltage supply with a fastening end signal. CONSTITUTION:A driver bit is rotated with rotation of a motor 19 via a plane tary differential so as to start fastening of a screw, and a transmission ring rotates according to the load on the bit, and the reduction ratio becomes infinity, and the driver bit rotating will stop. The load current of motor 19 increases according to the load on the driver bit, that is sensed by a sensing means 47 to be compared with a set value A on a setting device 51, and if in coincidence, a conversion command signal f is supplied to an A-D converter 54 after a cer tain period of time for conversion into digital, and a conversion end signal g is fed to a regular rotation control part 42 to stop the motor 19. This signal is supplied to a pulse generator 60 after stop of motor rotation is checked, and a signal i with a certain time width is fed to a reverse rotation control part 46 to operate the motor 19 reversely for reduction of the bit load so as to make smooth the separation at the time of rising return.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention completely eliminates the influence of oiliness of the driver bit when screw tightening is completed, and ensures the desired screw tightening with torque. The present invention relates to a control device for an automatic screw tightening machine.

PRIOR TECHNOLOGY In general, when controlling the screw tightening torque, the driver pin 1 is rotated by a rotational drive source, and the load 1 to applied to the driver pin 1 is measured using an appropriate detection means. A common method is to detect this and, when the detected value reaches a set value, stop the rotational drive source. in this way,
If the set value of screw tightening 1 herk is low, the screw tightening will be completed due to the influence of n nature of the rotary drive part.
- The torque exceeds the set value and the silk screw cannot be tightened accurately. Therefore, there is a need for a screw tightening machine that can accurately tighten screws even at low torque settings.

Problems to be Solved by the Invention As disclosed in Japanese Patent Publication No. 57-13211, the present invention provides a rotary drive source in which the transmission system from the input shaft to the output shaft includes a plurality of planetary cones with planetary motion. A non-rotating speed change ring that is commonly frictionally engaged with the conical surfaces of the plurality of planetary cones, and a concave transmission surface that is frictionally engaged with the input disk on the input shaft and a cam on the output shaft. In a frictionless transmission in which a flat transmission surface that frictionally engages with a disk is provided on a planetary cone, a speed change ring is automatically moved in a direction to reduce the rotational speed of an output shaft as load torque increases. The output side of the automatic transmission is connected to a driver bit and tightened by a screw, which is tightened by turning on the rotary drive source when the torque reaches a set value. Without stopping, the rotation of driver bits 1 to 1 is brought to zero, and the output torque at this time is used to maintain the tightening torque, and to prevent the biting between the driver bit and the screw head that occurs when screw tightening is completed. This solves the problem caused by

Means for Solving the Problems The present invention aims to eliminate the above-mentioned drawbacks, and includes a rotary drive source, an input disk that rotates in response to the rotation thereof, a planetary cone that frictionally engages with the outer periphery of the input disk, and a planetary cone that frictionally engages with the outer periphery of the input disk. The driver bit is connected via an engaging cam disc. Further, a speed change ring is disposed on the outer periphery of the planetary cone and is frictionally engaged with the conical surface thereof, and is configured such that the reaction torque applied to the speed change ring due to the load torque related to the driver bit is received by an elastic holding member. ing.

On the other hand, a forward rotation voltage supply section and a reverse rotation voltage supply section are connected to the rotational drive source via a switching means.

Further, a detection means for detecting the completion of screw tightening is arranged, and the output of this detection means operates the switching means to cut off the forward rotation voltage supply section and turn on the reverse rotation voltage of the reverse rotation voltage supply section for a predetermined period of time. The rotary drive source is configured to be supplied with the rotary drive source.

Function: In the control device for the automatic screw tightening machine described above, a normal rotation voltage is supplied to the rotational drive source to drive it, and the rotation is transmitted to the driver bit at a reduction ratio determined by the frictional engagement position of the speed change ring with the conical surface of the planetary cone. and then tighten the screws. When the screw is tightened, a reaction force of 1-lux is applied to the speed change ring in accordance with the load on the driver bit. Along with this, the speed change ring rotates and moves in the direction of its axis, and its reduction ratio increases until it reaches infinity, and the driver bit stops rotating, completing screw tightening. do. In accordance with this, the detection means for completing screw tightening is activated, and the switching means is activated by its output signal to cut off the supply of normal rotation voltage to the rotational drive source.

At this time, since the straight line connecting the contact points of the planetary cone, the speed change ring, and the cam disk is approximately parallel to the planetary cone, the cam disk is locked by the wedge action. Thereafter, a reverse voltage is supplied from the reverse voltage supply section to the rotational drive source for a predetermined period of time, and the rotational drive source rotates slightly in the reverse direction and then stops. Therefore, the planetary cone and the speed change ring are slightly reversed from the rotational drive source side, and the frictional engagement position is slightly returned to the high speed side. By returning the frictional engagement position to the high-speed side, the gear ring, cam disc, and planetary cone are unlocked, and at the same time, the load on the driver bit is reduced by reversing the rotational drive source. The gear ring rotates back to the high speed side until it reaches this position, and finally returns to its original position.

The driver bit then rises and prepares for the next operation.

EXAMPLE Hereinafter, an example will be described with reference to the drawings. In FIGS. 1 and 2, A is a control device for the automatic screw tightening machine 1, which is configured to be driven according to the flowchart shown in FIG. Prior to explaining the control device, the automatic screw tightening machine of the present invention shown in FIG. 4 will be explained. This automatic screw tightening machine 1 has a motor 19 as a rotational drive source fixed to one end of a driver main body 18, and receives the rotation of the motor 19, and receives an input circle that forms a part of the differential 'fL star machine side 20. The plate 21 is arranged to rotate. Further, a plurality of planetary cones 23 are arranged on the outer periphery of the input disk 21, and the circumferential grooves 23a of the planetary cones 23 are configured to frictionally engage with the input disk 21 to rotate.

A cam disk 24 rotating concentrically with the input disk 21 is disposed in a 1f frozen engagement with a flat surface 23b located at the center of the conical surface 23c of the planetary cone 23. Furthermore, a driver bit (not shown) that rotates integrally with the cam disc 24 is connected to the cam disc 24, so that the rotation of the motor 19 is transmitted to the driver bit.

Further, a conical surface 23 is provided on the outer periphery of the planetary cone 23.
A speed change ring 25 is arranged so as to rotate in frictional engagement with the speed change ring 25. This speed change ring 25 is rotatably held by an arm 32 whose one end is rotatably held.

Moreover, the speed change ring 25 is biased by a spring 31 so that its frictional engagement position is located on the high speed side. The maximum value of the reduction ratio determined by the frictional engagement position and the tightening torque are regulated. In this automatic screw tightening machine 1, the speed change ring 25 is rotated by a reaction torque generated in response to the tightening torque applied to the driver bit. The amount of movement in the axial direction due to the rotation of the speed change ring 25 is regulated by the spring 31, so that the pressing force on the spring 31 generated on the speed change ring 25 due to reaction torque and the elastic force generated due to the deflection of the spring 31 are combined. The speed change ring 25 is configured to move to a position where the speed change ring 25 is balanced. Therefore, when the load on the driver bit increases, the speed change ring 25 moves to the edge of the planetary cone 23, the driver bit is decelerated to zero rotation, and the screw is tightened as shown in the characteristic curve shown in FIG. .

Further, the control device A is configured to control a motor 19 as a rotational drive source of the automatic screw tightening machine. This control device has a work start section 41 , and this work start section 41 is connected to a forward rotation control section 42 . A forward rotation voltage supply section 43 and a reverse rotation voltage supply section 44 that supplies a reverse rotation voltage lower than the normal rotation voltage are connected to the motor 19 via a switching means 45. This switching means 45
supplies a forward rotation voltage to the motor 19 according to a signal from the forward rotation control section 42, and also supplies an A/D converter 54 to be described later.
After cutting off the forward rotation voltage by the conversion completion signal from
It is configured to supply a reverse rotation voltage to the motor 19 in response to a signal from the reverse rotation control section 46 . Moreover, this switching means 45 is configured so that the forward rotation voltage and the reverse rotation voltage are not supplied at the same time.

Further, a first detection means 47 is connected to the motor 19 to detect the load current flowing through the armature winding, and this first detection means 47 detects the filter 48 and the gain correction section 49. There is. Furthermore, this first detection means 47 is connected to a second detection means 50 that detects the completion of screw tightening. The second detecting means 50 includes a first setting device 5 having a voltage value lower than the voltage value corresponding to the desired tightening torque of 1 to 1 torque as a set value in order to detect the completion of screw tightening.
1. A first comparator 52 that compares the detected value to this set value, and an AND output signal of the output signal of the first comparator 52 and the output signal of the third detecting means 55 described later, for a predetermined period of time. (T1) First delay circuit 5 that later transmits an output signal
It consists of 3. This first delay circuit 53 is
- It is configured to send a conversion command signal to the D conversion unit 54.

Further, the first detection means 47 is connected to a third detection means 55 that detects whether the motor 19 has stopped rotating.

This fifth detection means 55 has a second δq constant 5 having a set value close to zero in order to detect rotation stoppage of the motor 19.
6. It consists of a second comparator 57 that compares this first setting with the detected value, and when the set value and the detected value match, the second comparator 57 sends an output signal. It is configured.

The detected value of the first detecting means 47 is supplied to an A-D converter 54, and the output signal of the second detecting means 50 starts digital conversion of the analog detected value at the time when screw tightening is completely completed. , after the conversion is completed, this A-D converter 54
The conversion data is output at the same time as the conversion completion signal is sent from the converter. Further, the conversion data is supplied to a torque display unit 58, and is configured to be displayed as a torque value upon receiving the conversion completion signal.

On the other hand, the conversion completion signal is supplied to the forward rotation control section 42, and the normal rotation voltage supplied to the motor 19 based on the signal from the work start section 41 is cut off. Further, this conversion completion signal is supplied to the second delay circuit 59, and is configured to be delayed by the time (T2) necessary for the normally rotating motor 19 to stop. At the same time, this conversion completion signal waits for an output signal from the third detection means 55 to confirm that the rotation of the motor 19 has completely stopped, and is then supplied to the pulse generator 60. The motor 19 has a desired reverse rotation time (
An output signal corresponding to the pulse T3) is input to the reverse rotation control section 46, and the signal from the reverse rotation control section 46 operates the switching means 45, while the machine cycle completion detection section 61
The device is configured to operate the driver bit lifting means 62 via the driver bit to raise and return the driver bit.

Further, the detection value of the first detection means 47 is supplied to a third comparator 64 of the tightening quality determination section 63, and the lower tightening limit set in the third setting device 69 is compared with a voltage value corresponding to torque. It is configured to This third comparator 64 is configured to issue an output signal when these match, and is configured to detect insufficient tightening when this output signal is not issued. In addition, the cotton (=I quality determination section 63 sets the upper and lower limits of the tightening torque set in the fourth setting device 65 and the fifth setting device 66 with respect to the conversion data of the A-D converting section 54). It is configured to receive output signals from a fourth comparator 67 and a fifth comparator 68 that determine whether or not the values are within the range of values. It has a determination unit (not shown) that determines whether or not the time until completion of tightening is within a predetermined time, and receives the conversion completion signal and comprehensively determines the quality of screw tightening. Good or bad tightening quality indicator 7
It is configured to be displayed comprehensively as 0.

In the control device for the automatic screw tightening machine described above, as shown in FIGS. 2a and 2C, the output signal of the work start section 41 is supplied to the lifting means 62 of the driver bit, and the lifting means 62 is operated.
The driver bit moves down. At the same time, work start section 4
The output signal of 1 is supplied to the forward rotation control section 42, and the switching means 45 is actuated by the signal from the forward rotation control section 42, and as shown in FIG. A normal rotation voltage is supplied to the motor 19 .

As the motor 19 rotates, the input disk, planetary cone,
The driver bit rotates via a differential planetary mechanism consisting of a cam disk and a speed change ring, and screw tightening begins. At this time, the speed change ring rotates in accordance with the load applied to the driver bit I~, and its reduction ratio increases continuously, and finally, the reduction ratio becomes infinite and the rotation of the driver bit stops.

On the other hand, as shown in FIG. 2d, the load current of the motor 19 increases according to the load applied to the driver pin 1, so this load current is detected by the first detection means 47, and as shown in FIG. Then, the detected value is compared with the set value of the first setter 51. When the detected value and the set value match, a conversion command signal is supplied to the A-D converter 54 after a predetermined time (T1) from that point, as shown in FIG. Convert the detected value at that point into digital data,
This conversion data is displayed on the torque display section 58. At the same time as this conversion is completed, a conversion completion signal is supplied to the normal rotation control section 42 as shown in FIG. 2g, and the rotation of the motor 19 is stopped.

On the other hand, the conversion completion signal is delayed by the time (T2) required for the motor 19 to normally stop, as shown in the second diagram. At the same time, this conversion completion signal is supplied to the pulse generator 60 after waiting for the output signal of the third detection means 55 and confirming that the motor 19 has stopped rotating, as shown in FIG. 2i. The pulse generator 60 generates a pulse signal having a predetermined time width (T3) as shown in FIG. 2J, and supplies this to the reverse rotation controller 46. The reversal control section 46 operates the switching means 45 while the pulse signal is being transmitted, and supplies a reversal voltage to the motor 19 from the reversal voltage supply section 44 . 'E
- The motor 19 rotates slightly in the opposite direction and stops, but as the motor 19 rotates in the opposite direction, the planetary cone and the speed change ring are reversed.

Therefore, the frictional engagement position between the planetary cone and the speed change ring returns to the high speed side, the lock of the speed change ring, cam disk, and planetary cone is released from the motor 19 side, and the reaction torque corresponding to the load on the driver bit changes the speed. transmitted to the ring. At this time, the load applied to the driver bit is
[-Since it has been reduced due to the reverse rotation on E19,
Depending on the load, the speed change ring returns along the conical surface of the planetary cone and finally returns to its original position. Further, the pulse signal from the pulse generating section 60 as shown in FIG. 2j is supplied to the machine cycle completion detecting section 61, and the output signal thereof is supplied to the lifting means as shown in FIG. to raise the dry pits 1~ in preparation for the next work.

At this time, since the reverse rotation voltage is sufficiently smaller than the forward rotation voltage as shown in FIG.
This load is small, and there is no possibility that the driver pins 1 to 1 will be reversed.

Furthermore, a third
The comparator 64 compares the lower limit tightening value of the third setter 69 with the detected value and the set value corresponding to the torque, thereby monitoring whether there is any abnormality in the torque transmission system. In addition, the above A-D
The conversion data of the conversion unit 54 is compared with the upper and lower limit setting values of the tightening torque of the fourth setting device 65 and the fifth setting device 66, respectively, and the torque required for tightening the screw is determined. The time is compared with the set time, and the state of the screw tightening is determined based on the time.A tightening quality judgment section 63 comprehensively determines whether the screw tightening work is good or bad, and a tightening quality display section 70 is displayed.

Note that the torque display section 58 and the tightening quality display section 70
is reset by a signal from the next work start section 41.

As described in detail, the present invention transmits the rotation of a rotary drive source to a driver bit through a differential f1 star mechanism consisting of an input disk, a planetary cone, a cam disk, and a speed change ring. The movement of the speed change ring in the axial direction is restricted by an elastic retaining member, and a detection means is provided to detect the completion of screw tightening.The output signal of the detection means stops the supply of normal rotation voltage to the rotational drive source, and then the rotational drive is stopped. Since the power source is configured to supply reverse voltage to the rotational drive source for a predetermined period of time, even if the differential planetary mechanism stops in the locked state when screw tightening is completed, this can be applied from the rotational drive source to the planetary cone. By rotating the speed change ring and the speed change ring in the reverse direction, the speed change ring can be rotated and returned to its original position according to the load on the driver bit by slightly changing its frictional engagement position, and finally returned to its original position, raising the driver bit. Even when returning, the driver bit smoothly separates from the screw, eliminating the need to lift the workpiece.
There are advantages such as no damage to screw heads or driver bits.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a signal waveform diagram at each point in FIG. FIG. 5, which is a sectional view of the main parts of the tightening machine, is a torque-rotational speed characteristic curve diagram of the output shaft of the automatic transmission according to the present invention. 8 Control device, 1 Automatic screw tightening machine, 18 Driver body, 19 Motor, 20
Differential planetary mechanism, 21 Human power disc, 23
Planetary cone, 23a circumferential groove, 23b flat surface,
23c round pin, 24 cam disc,
25 speed change ring, 31 spring,
32 Arm, 41 Work start part, 42
Forward rotation control section, 43 Forward rotation voltage supply section, 44
Reversing voltage supply section, 45 Switching means, 46
Reverse control section, 47 First detection means, 48
filter, 49 gain correction section, 50 second detection means, 51 first setter, 52 first comparator, 53 first delay circuit, 54 A-
D conversion unit, 55 third detection means, 56 second
Charcoal determiner, 57 Second comparator, 58 Torque display section, 59 Second delay circuit, 60 Pulse generation section, 61 Machine cycle completion detection section, 62 Lifting means,

Claims (1)

[Claims] A driver bit is connected via an input disk 21 that rotates in response to rotation of a rotational drive source, a planetary cone 23 that frictionally engages with the outer periphery of the input disk 21, and a cam disk 24 that frictionally engages with the input disk 21. At the same time, a speed change ring 25 that is frictionally engaged with the outer periphery of the planetary cone 23 is arranged so that the reaction force applied to the speed change ring 25 due to the load torque related to the driver bit is received by the elastic holding member. The forward rotation voltage supply section 43 and the reverse rotation voltage supply section 44 are connected through the switching means 45, and a detection means for detecting the completion of screw tightening is provided, and the switching means 45 is actuated by the output of this detection means. After the forward rotation voltage supply section 43 is cut off, the reverse rotation voltage of the reverse rotation voltage supply section is supplied to the rotation drive source for a predetermined period of time. The frictional engagement position is slightly returned to the high speed side from the rotational drive source side, and the speed change ring 25 is configured to rotate back to the high speed side in response to the load on the driver bit that is reduced by reversing the rotational drive source. A control device for an automatic screw tightening machine characterized by: