JPH0478422B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is capable of completing screw tightening on all axes even when each axis is affected by each other when simultaneously tightening multiple screws on one workpiece. The present invention relates to a multi-spindle screw tightening machine configured to maintain the tightening torque at a desired value.

Prior Art Generally, when tightening multiple screws on one workpiece at the same time, a multi-spindle screw tightening machine is used, which has multiple driver bits that rotate in response to the rotation of a rotary drive source attached to a driver stand. has been done. In order to control the screw tightening torque, this multi-spindle screw tightening machine uses an appropriate detection means to detect the load torque applied to the driver bit of each axis that rotates in response to the rotation of the rotary drive source. A control device is used that stops the rotary drive source when the value reaches a set value. In this control device, when the tightening torque of a certain axis reaches a predetermined value and the mode stops and tightening is completed, if the driver bit of the other axis is rotating, the tightening of this axis will proceed. As a result, the tightening torque of the shaft that was tightened first may be lower, and by the time all shafts have been tightened,
There is a drawback that the tightening torque of all the shafts does not reach a predetermined value, making it impossible to perform accurate tightening. As a device to eliminate this drawback,
There is a device described in the -56146 publication. This device is equipped with a timer device that allows the nut runner to output a constant tightening torque for a predetermined period of time even after all the screws have reached the predetermined tightening torque. Even if the bolt that has reached the specified torque is affected by the shaft that completes tightening last, it will not loosen and multiple screws will be reliably tightened to the specified tightening torque. .

Problems to be Solved by the Invention This device is configured so that the output of the nut runner continues to act for a predetermined time even after all the screws reach a predetermined tightening torque. Due to the influence of inertia of the nut runner, the final tightening torque has reached a predetermined value or higher. Therefore, even if the output of the nut runner is kept constant after that and it continues to work, all the tightening torques of all the screws have already exceeded the predetermined value, so all the tightening torques will not loosen below the predetermined value. However, there are drawbacks such as the impossibility of keeping the final tightening torque constant. In addition, with this device, the time required for tightening is longer, such as when tightening a tuft pin screw, and the variation in the time required to complete tightening is large.
If more than a predetermined amount of time elapses after the last shaft completes tightening, the shaft that completed tightening first will finish tightening last. It may loosen due to the influence of the shaft, and depending on the setting time, the initial purpose may not be achieved. Furthermore, if the shaft that was tightened first becomes loose just before the last shaft completes tightening, the driver bit of the loosened shaft may be retightening when the final shaft is tightened. A predetermined time has elapsed since the tightening was completed, and the driver bit stops during the retightening process, which also causes drawbacks such as not being able to maintain a constant tightening torque on all shafts.

Means for Solving the Problems The present invention aims to eliminate the above-mentioned drawbacks.
A driver stand that is raised and lowered by the operation of an elevating means is arranged, and a plurality of driver bodies are arranged on this driver stand so as to move together. A rotary drive source is attached to each of the driver bodies, and each of the rotary drive sources includes an input disk that rotates in response to the rotation, a planetary cone that frictionally engages with the outer periphery of the input disk, and a planetary cone that frictionally engages with the input disk. A driver bit is connected via a cam disk. Furthermore, a speed change ring is arranged on the outer periphery of the planetary cone and is frictionally engaged with the planetary cone. has been done.

A normal rotation voltage supply section is connected to each of the rotation drive sources via a switching means. Further, each of the driver bits is provided with a rotation stop detection means for detecting the stoppage thereof, and when a detection signal is received from the rotation stop detection means for all axes, the switching means for all axes is actuated to drive the rotation of all axes. An all-shaft tightening completion detection section is provided that transmits a detection signal to cut off the supply of normal rotation voltage to the power source.

Function The multi-spindle screw tightening machine described above has a
A normal rotation voltage is supplied to the rotation drive source, and the rotation is transmitted to the driver bit at a reduction ratio determined by the frictional engagement position between the planetary cone and the speed change ring, and the driver bit tightens the screw. As the screw is tightened, a reaction torque of the gear ring is applied in accordance with the load torque related to the driver bit. Along with this, the speed change ring rotates, but since the speed change ring is locked by the arm, the speed change ring moves in the direction of its axis, and its reduction ratio increases until it reaches infinity. Then, the rotation of the driver bit stops. At this time, the rotary drive source continues to rotate, but the driver bit does not rotate and continues to output a predetermined tightening torque.

Along with this, the rotation stop detection means for detecting the rotation stop of the driver bit is activated and a detection signal is sent, and the rotation stop detection means for all the shafts is activated until the detection signal is sent from the rotation stop detection means for all the shafts, that is, the tightening is completed first. This state is maintained regardless of the time from the point in time. When the detection signals are transmitted from all the axes, the switching means is immediately activated to cut off the supply of normal rotation voltage to the rotation drive source. At this time, the planet cone and speed change ring,
Since the straight line connecting the respective contact points of the cam discs is substantially parallel to the planetary cone, the cam discs are held in a locked state by the wedge action, and the driver bit outputs the tightening torque value.

Thereafter, a reversing voltage is supplied to the rotational drive source for a short time, the rotational drive source rotates slightly in reverse and stops, and the locking state of the speed change ring, cam disc, and planetary cone is released from the drive source side. . At the same time, the speed change ring returns along the conical surface of the planetary cone to a position corresponding to the load torque of the driver bit reduced by the reversal of the rotational drive source, and finally returns to its original position. After that, the driver bit increases and prepares for the next operation.

Embodiments Hereinafter, embodiments will be described with reference to the drawings. In FIGS. 2 and 3, 1 is a multi-shaft screw tightening machine, and this multi-shaft screw tightening machine 1 includes a driver stand 3 that is raised and lowered by the operation of a lifting means 2 consisting of a cylinder, and a driver stand 3 that is integrated with this at a predetermined interval. It has a desk 4 which is movable and relatively movable. A chuck unit 5 having a pair of chuck claws 5a for holding a desired screw is fixed to the chuck base 4 in correspondence with each driver bit 6 to be described later. Further, a plurality of driver bodies 7 are fixed to the driver stand 3, and a motor 8 as a rotational drive source is fixed to each of the driver bodies 7. (Hereinafter, one shaft of the driver bit will be explained.) On the drive shaft of the motor 8, an input disk 10, which is a part of a differential planetary mechanism 9 forming an automatic transmission, is arranged so as to rotate in response to the rotation thereof. has been done. A cone holder 1 is attached to the outer periphery of this input disk 10.
A plurality of planet cones 12 held by the input disk 1 are disposed, and the circumferential grooves 12a thereof are configured to frictionally engage with the input disk 10 and rotate. A cam disk 13 rotating concentrically with the input disk 10 is arranged so as to frictionally engage with a flat surface 12b located on the back side of the conical surface 12c of the planetary cone 12. Moreover, this cam disk 13
The driver bit 6 is connected via a connecting mechanism 15 including a connecting shaft 14 rotatably held in an inner cylindrical portion 7a fixed to the driver stand 3, and two universal joints 15a connected to the connecting shaft 14. The rotation of the motor 8 is transmitted to the driver bit 6.

Furthermore, a speed change ring 16 is arranged on the outer periphery of the planetary cone 12 so as to rotate by frictionally engaging with the conical surface 12c of the speed change ring 16.
is rotatably held by an arm 17 whose one end is rotatably held on the driver stand 3 side. In addition, the speed change ring 16 is biased by a spring 18 so that its frictional engagement position is located on the high speed side, and the elastic retaining member consisting of the spring 18 and the arm 17 allows the speed change ring 16 to be frictionally engaged. The position is regulated and the maximum rotational speed and tightening torque of the driver bit 6 are determined. In this multi-shaft screw tightening machine 1, the speed change ring 16 is rotated by the reaction torque generated in response to the tightening torque applied to the driver bit 6, but the amount of movement in the axial direction due to the rotation of the speed change ring 16 is 18, the speed change ring 16 is configured to move to a position where the pressing force on the spring 18 generated by the reaction torque and the elastic force generated by the deflection of the spring 18 are balanced. There is. Therefore, driver bit 6
As the load on
is decelerated until it reaches zero rotation, and outputs a tightening torque as shown in the characteristic curve shown in FIG.

Further, the motor 8 is controlled by a control device A shown in FIG.
controlled by This control device A has a work start part 21, and this work start part 21 is connected to a normal rotation control part 22 and the lifting means 2,
When the work start signal is transmitted, the elevating means 2 is operated, and the forward rotation control section 22 is configured to transmit a forward rotation command signal for operating the switching means 23. The motor 8 includes a forward rotation voltage supply section 24 and a reverse rotation voltage supply section 25 that supplies a reverse rotation voltage lower than the forward rotation voltage.
Connected via 3. This switching means 23 receives a forward rotation command signal from the forward rotation control section 22 and supplies a forward rotation voltage to the motor 8, and also receives a cutoff command signal from an all-shaft tightening completion detection section 26, which will be described later. After cutting off the rotation voltage, the motor 8 is configured to receive a rotation command signal from the rotation control section 27 and supply the rotation voltage to the motor 8 .

Further, a rotation detecting section 28 for detecting the rotation of the driver bit 6 is attached to the lower part of the front driver stand 3.
It consists of As shown in FIG. 5, the rotation detection section 28 includes a slit disk 28a fixed to the connecting mechanism 15 that rotates together with the driver bit 6, and a sensor section disposed corresponding to the movement path of the slit at one end of the slit disk 28a. (not shown), and is configured so that when the slit of the slit disk 28a passes through the sensor section, an output pulse is transmitted. This rotation detection section 28 is connected to a rotation stop detection section 29 via an amplification section 31, a waveform shaping section 32, and a differentiation circuit 33. The rotation stop detection section 29 is composed of a timer TA, which is an example of a pulse width detector, and a flip-flop FF, which is an example of a memory. After the elapsed time, the output pulse from the rotation detection section 28 is detected by the timer TA.
The timer TA is reset and immediately after a very short time T2 determined by the second delay circuit 34 has elapsed, the timer TA is set. Moreover, this timer TA is set and the timer TA is
If an output pulse is not transmitted from the rotation detection section 28 within a period of time, the output signal is output to the flip-flop FF,
In response to this output signal, the flip-flop FF is configured to output an output signal as a detection signal of the rotation stop detection section 29.

The rotation stop detection means 30 is arranged on each axis, and the output signals of the rotation stop detection section 29 are all supplied to an all-axis tightening completion detection section 26 consisting of an AND circuit and a holding circuit 35. has been done. Further, when the all-axis tightening completion detection unit 26 receives the detection signals from all the axes, the AND circuit transmits a coincidence signal, and furthermore, based on this coincidence signal, the holding circuit 35 continuously transmits a detection signal. It is configured to The detection signal of the holding circuit 35 is supplied to the forward rotation control section 22 as a detection signal of the all-shaft tightening completion detection section 26, and the forward rotation control section 22 supplies a cutoff command signal to the switching means 23, so that the motor 8 It is configured to cut off the normal rotation voltage to. Further, the detection signal is supplied to a third delay circuit 36, delayed by a time T3 necessary for the normally rotating motor 8 to stop, and then supplied to the pulse generator 37. . This pulse generating section 37 transmits a pulse signal of a desired reversal time to the reversal control section 27, and a reversal command signal is transmitted from the reversal control section 27, the switching means 23 is activated, and the motor 8 can be reversed for a predetermined period of time. It is configured. Further, the pulse generating section 37 is configured to cause the elevating means 2 to move back through the machine cycle completion detecting section 38 to return the driver bit 6 to the upper position.

In the above multi-shaft screw tightening machine, the work start part 21
The lifting means 2 is activated by the work start signal.
Driver bit 6 falls. At the same time, the work start signal from the work start section 21 is transmitted to the forward rotation control section 22.
A forward rotation command signal is supplied from the forward rotation control section 22 to the switching means 23, the switching means 23 is operated, and the forward rotation voltage is supplied to the motor 8 from the forward rotation voltage supply section 24. As the motor 8 rotates, the driver bit 6 rotates via a differential planetary mechanism 9 consisting of an input disk 10, a planetary cone 12, a cam disk 13, and a speed change ring 16, and screw tightening is started. Along with this, the slit disk 28a rotates, so that the rotation detection section 28 outputs an output pulse. After this output pulse is waveform shaped,
It is supplied to the rotation stop detection section 29. Said timer
If this output pulse is continuously supplied before TA has counted the predetermined time TA, the timer TA is reset by the next output pulse and the timer TA does not emit an output signal. Also, the timer TA is set immediately after being reset to prepare for the next output pulse. In this state, as the screw tightening progresses, the speed change ring 16 rotates in response to the load applied to the driver bit 6, and its reduction ratio increases continuously until the reduction ratio reaches infinity. The rotation of the driver bit 6 stops. When the rotation of the driver bit 6 stops, the output pulse from the rotation detecting section 28 is no longer transmitted, and the timer TA counts the predetermined time TA and transmits an output signal. Therefore, the output of the flip-flop FF is inverted, and its output signal is sent to the all-axis tightening completion detection section 26, which waits for detection signals from the rotation stop detection section 29 of the other axes. When a detection signal is sent from the rotation stop detection section 29 of the last axis, a coincidence signal is sent from the AND circuit. At this time, if the shaft that was tightened first becomes loose and the driver bit rotates just before the rotation stop detection signal is sent from the last shaft, the rotation of this shaft will stop and rotation stop will be detected. You can wait for the signal to be believed. When the AND circuit generates a match signal, the holding circuit 35 generates an output signal. The output signal of this holding circuit 35 is supplied as a cutoff command signal to the forward rotation control section 22 to operate the switching means 23 to cut off the forward rotation voltage.
At the same time, the output signal of the holding circuit 35 is supplied to a third delay circuit 36, delayed by the time T3 necessary for the motor 8 to normally stop, and supplied to the pulse generator 37.

This pulse generator 37 generates a pulse signal with a predetermined time width, and supplies this to the reverse rotation control section 27 as a reverse rotation command signal. The reversal control section 27 operates the switching means 23 while the pulse signal is being transmitted, and supplies the reversal voltage from the reversal voltage supply section 25 to the motor 8.
supply to. The motor 8 rotates slightly in the opposite direction and then stops, but as the motor 8 rotates in the opposite direction, the planetary cone 12 and the speed change ring 16 rotate in the opposite direction. Therefore, the frictional engagement position between the planetary cone 12 and the speed change ring 16 returns to the high speed side, and the locked state of the speed change ring 16, cam disc 13, and planetary cone 12 is released from the motor 8 side, and the load on the driver bit 6 is released. The reaction torque corresponding to the shift ring 16
is transmitted to. At this time, the load applied to the driver bit 6 is reduced as the motor 8 rotates in the opposite direction, so the speed change ring 16
returns along the conical surface of the planetary cone 12, and finally returns to its original position.

Further, the pulse signal from the pulse generator 37 is supplied to the machine cycle completion detector 38, and its output signal is supplied to the lifting means 2, which is actuated to raise the driver bit 6 in preparation for the next work. .

Effects of the Invention As explained above, the present invention transmits the rotation of a rotary drive source to a driver bit through a differential planetary mechanism consisting of an input disk, a planetary cone, a cam disk, and a speed change ring, thereby transmitting the rotation of a rotational drive source to A plurality of screw tightening machines are arranged so that movement in the direction is restricted by elastic holding members, and each driver bit is provided with a rotation stop detection means for detecting the stop of the screwdriver bit, and furthermore, a rotation stop detection means for all axes is installed. Since the rotary drive source is configured to stop only after the detection signal is sent, even if the rotary drive source is rotating at high speed, the rotation of the driver bit will stop when tightening is completed, and each shaft will not be tightened. Not only can this be done without the influence of inertia, but when tightening multiple screws on one workpiece at the same time, the screw that completed tightening first will loosen due to the influence of the shaft that completes tightening last. If something like this happens, it has the advantage of being able to be retightened each time. Furthermore, even if there is variation in the time required for tightening each shaft, the voltage to the rotational drive source of the shaft that completed tightening first is cut off before the last shaft completes tightening. Not only does this not happen, but even if the shaft that was tightened first loosens just before the last shaft finishes tightening, and the driver bit of that shaft rotates, the driver bit will not rotate. The voltage to the rotational drive source is not cut off until all axes have stopped.
This has the advantage that all the shafts are held so that they can be driven again, and that all the shafts can be reliably held at a predetermined tightening torque.

Furthermore, in the present invention, when the torque applied to the driver bit reaches a predetermined value upon completion of tightening, the rotation is stopped even if voltage is continued to be supplied to the rotational drive source, so there is no need for a mechanism to detect the torque applied to the driver bit. Completion of tightening can be detected simply by detecting the stoppage of the driver bit, and a torque converter for detecting the torque applied to the driver bit is not required, making it possible to provide an inexpensive screw tightening machine.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a control device according to the present invention, FIG. 2 is an overall explanatory diagram of a multi-shaft screw tightening machine according to the present invention, and FIG. 3 is a sectional view of essential parts of a multi-shaft screw tightening machine according to the present invention. , FIG. 4 is a torque-rotational speed characteristic curve diagram of the output shaft of the automatic transmission according to the present invention,
FIG. 5 is a block diagram of essential parts for explaining the rotation stop detection means according to the present invention. A...Control device, 1...Multi-spindle screw tightening machine, 2...Elevating means, 3...Driver stand, 4...Chuck stand, 5...Chuck unit, 5a...Chuck pawl, 6...Driver bit, 7...Driver body, 7a...Inside Cylinder part, 8
...Motor, 9...Differential planetary mechanism, 10...Input disk,
11... Cone holder, 12... Planetary cone, 12a
...Circumferential groove, 12b...Flat surface, 12c...Conical surface, 1
3... Cam disk, 14... Linking shaft, 15... Linking mechanism, 15a... Universal joint, 16... Speed change ring, 17... Arm, 18... Spring, 21... Work start part, 21a... First delay circuit, 22... Positive Rotation control section, 23... Switching means, 24... Forward rotation voltage supply section, 25... Reverse rotation voltage supply section, 26... All shaft tightening completion detection section, 27... Reverse rotation control section, 28... Rotation detection section,
28a...Slit disk, 29...Rotation stop detection unit,
30... Rotation stop detection means, 31... Amplifying section, 32...
Waveform shaping section, 33... Differentiating circuit, 34... Second delay circuit, 35... Holding circuit, 36... Third delay circuit, 37
...Pulse generation section, 38...Machine cycle completion detection section.

Claims (1)

[Claims] 1. A driver stand 3 that is raised and lowered by the operation of the elevating means 2 is arranged, a plurality of driver bodies 7 are arranged on this driver stand 3 so as to move together, and each of these driver bodies 7 has a rotating mechanism. A drive source 8 is attached, and an input disk 10 that rotates in response to the rotation of each rotary drive source 8, a planetary cone 12 that frictionally engages with the outer periphery of the input disk 10, and a cam disk 13 that frictionally engages with this A speed change ring 16 that connects the driver bit 6 and frictionally engages with the outer periphery of the planetary cone 12 is arranged, and this speed change ring 16 is rotatably held by an arm 17 attached to the driver stand 3 side. spring 18
In a multi-spindle screw tightening machine in which the speed change ring 16 is biased to the high speed side, the normal rotation voltage supply section 24 is connected to each of the rotation drive sources 8 via the switching means 23, and the stoppage of each of the driver bits 6 is detected. A rotation stop detection means 30 is provided to switch all axes when a detection signal is received from the rotation stop detection means 30 for all axes.
A multi-shaft screw tightening machine characterized by being provided with an all-shaft tightening completion detection unit 26 that transmits a detection signal that activates the rotational drive source 8 of all the axes to cut off the supply of normal rotation voltage to the rotational drive source 8 of all the axes.