JPH09240618A - Pacing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packing machine provided with a controller for preventing the press force of a pinch roller to a feed roller from the change or reducing the change even if the valve of feed AC voltage fed to a solenoid is changed when the press force of the pinch roller is adjustable changed by changing the duty ratio of the feed AC voltage. SOLUTION: This packing machine is provided with a delivering and tightening mechanism having a solenoid type actuator for adjusting the press force of a pinch roller 40 to a feed roller 30, and a controller C. The controller C is provided with a DC chopper controlling circuit 50 for phase controlling AC voltage fed to the solenoid actuator 45, a threshold value cross point detecting circuit 51 for outputting signals of threshold value cross points C1 , C2 in AC voltage wave forms U1 , U2 fed to a DC chopper controlling circuit 50 and a solid state relay SSR. The DC chopper controlling circuit 50 has a variable resistor 50c capable of changing chopper phase angle τ1 , τ2 of the fed AC voltage, and the calculation starting points of the chopper phase angle τ1 , τ2 are set on the basis of the threshold value cross detecting circuit 51.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packing machine in which a band is wrapped around an object to be packed and the band is tightened, and at the same time, a superposed portion of the band is heated and melted and press-bonded to bind the banding device. The present invention relates to a packing machine including a control device that controls a power supply to a driven solenoid type actuator.

[0002]

2. Description of the Related Art Conventionally, in this type of packing machine, a band feeding and tightening mechanism sandwiches a band between a pair of rollers driven by a motor in order to draw the band around an object to be packed placed on a work table. After sending out, the band is wound around the outer peripheral surface of the object to be packed, and the excess of the wound band is pulled back by the pair of rollers at high speed and low torque. Secondary tightening is performed, and then, the superposed portion of the front end and the rear end of the band is heated and melted by a heater or the like provided in a band end processing mechanism including a cam mechanism driven by another motor, and It is well known that the melted portion is press-bonded by a press, cooled and joined to cut the rear end of the band.

The pair of rollers for sending out or pulling back the band is composed of a feed roller driven by the motor and a pinch roller pressed by the feed roller. The secondary tightening is
Usually, since the band is sandwiched between the pair of rollers and pulled back at a low speed and high torque for a predetermined time or length, the tightening force of the band by the secondary tightening on the object to be packed is It was determined by the tightening time or the length of the band to be pulled back by the secondary tightening.

However, since the objects to be packed by the packing machine have various sizes, shapes, rigidity, properties, etc., in the packing machine in which the secondary tightening is performed as described above, the size and shape are In order to obtain an appropriate tightening force for various objects to be packed having different rigidity, properties, etc., considerable skill is required. Since the packing work is not performed only by a skilled person, in the actual packing work, the tightening force is often excessive or insufficient, and problems such as removal of the band and damage to the object to be packed occur.

In order to improve the above-mentioned problems, the applicant has made the pressing force of the pinch roller against the feed roller variable so that the secondary tightening force of the band can be arbitrarily adjusted and set, and the variable adjustment is performed by a solenoid. We have previously proposed a pressure adjustment means that uses an actuator (Japanese Patent Application No. 7-8).
7185).

The pressure adjusting means adjusts the tightening force of the band with respect to the object to be packed by adjusting the magnitude of the pressing force of the pinch roller against the feed roller, that is,
By increasing the pressing force of the pinch roller, slippage between the band and the feed roller and pinch roller is less likely to occur, and the band can be strongly pulled during tightening, thereby increasing the tightening force. It is a thing.

The pressing force of the pinch roller against the feed roller is adjusted by controlling the phase of the AC voltage supplied to the solenoid type actuator using a DC chopper control circuit, and the phase of the AC voltage supplied is adjusted. This can be arbitrarily performed by a variable resistor incorporated in the DC chopper control circuit and operated from the outside of the packing machine to change the chopper phase angle. Therefore, the tightening force can be adjusted by simply operating the variable resistor from the outside, and desired secondary tightening can be performed according to the size, shape, rigidity, property, etc. of the object to be packed. is there.

The pressure adjusting means for varying the pressing force of the pinch roller with respect to the proposed feed roller and performing the variable adjustment with a solenoid type actuator is a circuit for supplying drive power to the solenoid type actuator and its control circuit. The circuit includes a circuit for supplying an alternating-current power supply (AC 100 V) to the solenoid type actuator via a solid state relay, a computer for controlling the phase of the voltage of the supplied power by the solid state relay, and a direct current chopper. It is composed of a voltage control circuit to which a DC power supply (DC5V) including a control circuit and a zero-cross point detection circuit is connected.

The zero-cross point detection circuit, as shown in FIG. 7, is a conversion point from the plus to the minus or from the minus to the plus of the waveform of the AC voltage of AC100V supplied to the solenoid type actuator, that is, the zero cross. A detection circuit for detecting a point, and an output signal of the zero-cross point is input to the chopper control circuit.

The conventional chopper control circuit described above is based on AC10.
Over chopper AC waveform U ₁ of 0V, the waveform of the shaded portion of the AC voltage waveform U ₁ part cut away of time t _1, varying the time t ₁ of the oblique line portion, that is, an AC voltage The electric power is output by changing the duty ratio t ₁ / T (T = constant). The chopper control circuit includes a transistor, an integrating circuit including a resistor and a capacitor, a reference voltage setting circuit including a variable resistor, and a comparator. By operating the variable resistor to change its resistance value. , by changing the reference voltage value is intended to change the position of the chopper phase angle r ₁ in the alternating voltage waveform U _1, by changing the duty ratio t ₁ / T of the AC voltage to change the output power by the change ing.

[0011]

The AC power supply for driving the solenoid actuator and for detecting the zero-cross point is usually supplied with a voltage of AC100V. However, for some reason, , For example, the power supply voltage is lower than AC100V,
That is, the supply voltage waveform U ₂ as shown by the dotted line in FIG. 7 may be supplied. Such a voltage fluctuation, that is, a difference in power supply voltage causes a difference in output power, and can be understood from FIG. 7 even if the duty ratios t ₁ / T of the two power supply voltages are the same. As described above, the driving force of the solenoid type actuator, that is, a change in the pressing force of the pinch roller appears, and when the voltage drops, a desired sufficient secondary tightening force based on the pressing force of the pinch roller is generated. There was a problem that it could not be given to the band.

When the power supply voltage changes, the variable resistor is operated to change the duty ratio of the power supply voltage so that the pinch roller can obtain a desired pressing force each time. There was a problem that it was necessary. The present invention has been made in view of such a problem, and an object thereof is to adjust a pressing force of a pinch roller against a feed roller by changing and adjusting a duty ratio of a supply AC voltage supplied to a solenoid. In a packaging machine to perform, there is provided a packaging machine provided with a control device that does not cause a difference in pressing force of the pinch roller even if the voltage value of the supplied alternating current changes, or can reduce the difference. .

[0013]

[Means for Solving the Problems] To achieve the above object,
A packing machine according to the present invention comprises a band delivery tightening mechanism having a solenoid type actuator for adjusting a pressing force of a pinch roller against a feed roller, and a control device, wherein the control device is a signal of a threshold cross point of a supply AC voltage waveform. A threshold crossing point detection circuit, a DC chopper control circuit for phase-controlling the AC voltage supplied to the solenoid actuator by receiving the threshold crossing point signal, and actuating in response to a signal from the DC chopper control circuit It is characterized by having a solid state relay that operates.

Further, the DC chopper control circuit includes a variable resistor capable of changing the chopper phase angle of the supply AC voltage, and the threshold cross point detection circuit detects the chopper phase angle calculation starting point by the threshold cross point detection circuit. It is characterized by being set based on points.

In the packing machine according to the present invention constructed as described above, by changing the resistance value of the variable resistor of the DC chopper control circuit, the time from the threshold cross point is changed and the reference voltage value is changed. Then, the inversion timing of the output signal of the DC chopper control circuit, that is, the position (timing) of the chopper phase angle in the AC voltage waveform is changed. As a result of this change, the duty ratio of the AC voltage is changed and the output is changed. That is, by changing the resistance value (reference voltage value) of the variable resistor, the chopper phase angle of the AC voltage waveform is changed from 0 ° to 180 ° (180 ° to 3 °).
It is possible to change continuously up to 60 °), and this change changes the duty ratio of the AC voltage to change the output power to 10
It can be changed from 0% to 0.

Furthermore, when the voltage of the power supply to the power supply changes, that is, when an electric power having a voltage value different from the normal value is input, the resistance value of the variable resistor of the DC chopper control circuit is the same. However, since the height of the AC voltage waveform varies depending on the voltage value of the power, the detection position of the threshold cross point of the threshold cross point detection circuit becomes different. The duty ratio is different due to the different detection position of the threshold cross point, and the duty ratio is controlled to be higher as the power has a lower voltage.

This is based on the fact that even if the voltage of the power supply power supply is lowered and the output power is lowered, the duty ratio is increased and the duty ratio is increased due to the voltage drop. As the output power is increased, the output does not decrease even if the voltage of the power supply decreases, or even if it decreases, the decrease can be reduced, and the pressing force of the pinch roller against the feed roller can be reduced. Can be minimized.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a packing machine 1 according to the present embodiment.
It is the front schematic diagram of 0, and has shown the example of an automatic type. The packing machine 10 includes a work table 1 on which an article W to be packed is placed.
An arch portion 15 for guiding a band is provided on a box-shaped main body housing 13 having 4 and a band reel 16 loaded with a band coil BC is stored and supported in the main body housing 13. Casters 19, 19, ... Are attached to the four corners of the bottom surface of the main body housing 13 so that the entire packing machine 10 can be easily moved.

The band reel 16 is a band coil B.
A drum 17 loaded with C, a reel shaft 16a that rotatably supports the drum 17, a band reel mounting member 18 to which one end of the reel shaft 16a is fixed, the band reel mounting member 18, and the drum. 17 and a band reel brake device 11 arranged between them.

Between the band reel 16 and the work table 14, a band filling / pool mechanism L including a pool feed roller 21, a pressing roller 22, a band guide 23, a pool chamber 24, etc., and a band filling / packing mechanism L.
A band delivery tightening mechanism S (described later in detail) for sending out and tightening the band B supplied from the pool mechanism L, and a superposed portion of the forward end and the rear end of the band B sent out and tightened is heated by a heater or the like. Then, the melted portion is pressed by a press or the like, cooled and joined to cut the rear end of the band B. Stepping motor M ₁
A banding mechanism including a band end processing mechanism K having a structure known per se, which is driven by.

Next, the band delivery tightening mechanism S will be described with reference to FIGS. As shown in FIG. 2, the band delivery tightening mechanism S is disposed on the lower right side portion of the work table 14, and is fed by a stepping motor M ₂ (see FIG. 3). A pinch roller 4 pressed against the feed roller 30 by pressure adjusting means composed of an actuator 45.
0. Below the rollers 30 and 40, a pair of longitudinal feed opposed band guides 25 and 26 for guiding the band B drawn from the band filling / pool mechanism L between the two rollers 30 and 40 are arranged. Further, a pair of lateral feed opposed band guides 27, 28 are arranged from the upper surface of the feed roller 30 toward the central portion of the work table 14. The feed roller 3
The tip of the band B sandwiched between 0 and the pinch roller 40 and fed out passes through the top of the band end processing mechanism K and is guided by the gate-shaped arch portion 15 to the working table 14 The object W to be packed placed on the upper part is looped around.

As shown in FIG. 3, the feed roller 30 is integrally fixed to a feed roller shaft 31 rotatably driven by the stepping motor M ₂ by a feather key 29, and the feed roller 30 is rotated by the rotation of the stepping motor M _2. The feed roller 30 is rotationally driven. The outer peripheral surface of the feed roller 30 is made of urethane rubber or the like, and is covered with a surface layer member 30a made of a material that is unlikely to slip with the band B.

On the other hand, the pinch roller 40 pressed against the feed roller 30 is rotatably attached to the eccentric large diameter portion 36a of the rotary support shaft 36 having the eccentric large diameter portion 36a via a pair of rolling bearings 44, 44. It is supported. The rotary support shaft 36 is rotatably supported by inner and outer support brackets 38, 39 via circular washers 37, 37 at both ends of the large diameter portion 36a. A slab-shaped release lever 41 is fixed to a projecting end portion of the rotation support shaft 36 outside the outer bracket 38 by a pin or a screw 42 so as to rotate integrally with the rotation shaft 36. As shown in FIG.
An upper end portion of a pulling arm 46 is rotatably connected to the release lever 41 from a central portion thereof to an upper left portion thereof via a pin 48 so as to be rotatable.
The lower end of 6 is a solenoid type actuator 45 which is an electric actuator attached to the support plate 33.
Is rotatably connected to the operating rod 45a of FIG.

The solenoid type actuator 45 is
When the built-in solenoid is not excited (when OFF)
The actuating rod 45a is relatively upwardly protruded by the urging force of a spring incorporated therein. On the other hand, when the built-in solenoid is excited (ON), the operating rod 45a retracts inward against the biasing force of the built-in spring. In this case, the retracted amount of the operating rod 45a is increased as the electric power (voltage) supplied to the built-in solenoid is increased.

When the operating rod 45a of the solenoid type actuator 45 is pulled inward, the release lever 41 is rotated counterclockwise in FIG. 2 through the pulling arm 46, and the rotary shaft is integrally formed with it. 36 is also rotated. Since the position of the center axis line pp of the eccentric large diameter portion 36a (pinch roller 40) is eccentric with respect to the center axis line o-o of the rotation support shaft 36 (release lever 41), the rotation support shaft 36 is When rotated, the pinch roller 40 swings to the left in FIG. 2, that is, toward the feed roller 30, and the pinch roller 40 passes through the band B passing between the pinch roller 40 and the feed roller 30. It is strongly pressed against the feed roller 30.

Therefore, the solenoid type actuator 45, the pulling arm 46, the release lever 4
1, and a rotary support shaft 36 including the eccentric large-diameter portion 36a
And the like constitute pressure adjusting means for varying the pressing force of the pinch roller 40 against the feed roller 30.

Next, focusing on the control circuit of the control device C of the packing machine 10 of the present embodiment, particularly the power supply circuit to the pressure adjusting means of the band delivery tightening mechanism S and its control circuit, FIG. A description will be given based on FIG. The control circuit of the control device C shown in FIG. 4 controls the solenoid actuator 45 via an AC power source U (AC10) via a solid state relay SSR.
0V) and a voltage to the solenoid type actuator 45 are connected to the solid state relay SSR.
It is composed of a computer CPU for controlling the phase by means of a DC chopper control circuit 50, and a voltage control circuit connected to a DC power source (DC 5V) including a threshold cross point detection circuit 51 and the like.

FIG. 5 shows an AC voltage waveform U of the supplied power source.
₁ is a diagram showing U ₂ and a phase control state thereof, wherein an AC voltage waveform U1 shows a regulated voltage waveform of AC100V which is normally supplied, and an AC voltage waveform U2 shows a voltage waveform lower than the waveform U1. There is. The plus and minus direction from the zero potential line which is drawn a line threshold Y _1, Y ₂ in the position of the predetermined potential a, threshold value Y _1, Y ₂ and the AC voltage waveform U1, U2
Points crossing the waveform toward the zero potential line are set as threshold crossing points C ₁ and C _2, and phase angles r ₁ and r ₂ after a predetermined time t _x elapses from the threshold crossing points C ₁ and C ₂ The period of the predetermined time t ₁ and t ₂ of the shaded portion up to the zero cross point is the effective period in which the electric power is applied to the solenoid actuator 45. That is, the solenoid actuator 45
Power applied to is between a predetermined time t _1, t ₂ of a portion cut away hatched portion of the AC voltage waveform U1, U2, by changing the predetermined time of the oblique line portion t _1, t ₂ , The output power is changed by changing the duty ratios t ₁ / T and t ₂ / T (T = constant) of the AC voltage.

[0029] The threshold cross point detection circuit 51, the AC voltage waveform U1, the waveform toward the zero potential line U2 threshold Y ₁ of the AC voltage supplied to the solenoid actuator 45, Y ₂ and cross Threshold crossing point C
_1, a detection circuit for detecting the C _2, and outputs an output signal of the threshold crossing point C _1, C ₂ in the transistor 50a of the DC chopper control circuit 50. FIG. 6 shows a waveform with time when the threshold cross points detection circuit 51 detects the threshold cross points C ₁ and C ₂ and outputs the threshold cross points C ₁ and C ₂ to the DC chopper control circuit 50.

The AC voltage waveforms U1 and U2 (see I) of the power source power supplied to the threshold value cross point detection circuit 51 are converted into full-wave rectified waveforms U1 and U2 by the pre-control circuit 51a (FIG. 4) and the threshold values are set. Y is set (see II). In the rear control circuit 51b (FIG. 4), first, the full-wave rectified waveforms U1, U
2 makes off-state square waves U1 ₁ , U2 ₁ (see III) between points C ₁ , C ₂ , C ₃ , C ₄ where ₂ crosses the threshold Y,
Subsequently, the said square wave U1 _1, U2 square wave on-state ₁ in the inverting circuit U1 _1, U2 ₂ (see IV). The square wave U
1 ₁ and U 2 ₁ become a square wave with a wider width as the voltage becomes lower. After that, the square waves U1 ₁ and U2 ₁ are differentiated, and the start point of the waveform is output as waveform signals U1 ₂ and U2 ₂ (V
Further, the waveform signals U1 ₂ and U2 ₂ are converted into a rectangular waveform U1.
₂ , C22 control circuit 5 as U2 ₂ (see VI)
Output to 0. The rectangular waveforms U1 ₂ and U2 ₂ are output earlier as the voltage becomes lower and are transmitted to the DC chopper control circuit 50.

The DC chopper control circuit 50 applies a chopper to the AC voltage waveform of the power source to generate a signal shown in FIGS.
Solid line I), and the AC voltage waveform U _1, the effective waveform between a predetermined time t _1, t ₂ of a portion cut away hatched portion of each U ₂ indicated by a dotted line, a predetermined time of the hatched portion in the respective The output power is changed by changing t ₁ and t ₂ , that is, by changing the duty ratios t ₁ / T and t ₂ / T (T = constant) of the AC voltages U ₁ and U ₂ , respectively. Each of the AC voltage waveforms U ₁ ,
The duty ratios t ₁ / T and t ₂ / T of U ₂ are changed by changing the time t _x from the threshold crossing points C ₁ and C ₂ so that the chopper phase angles r ₁ and r ₂ are changed. It is changed by changing the times t ₁ and t ₂ .

The DC chopper control circuit 50 includes a transistor 50 which receives signals at the threshold crossing points C ₁ and C _2.
a, an integrating circuit composed of a resistor and a capacitor, a reference voltage setting circuit, a comparator 50b, and the like. The two circuits include an integrating voltage and a reference voltage.
0b, the comparator 50b compares the magnitudes of the two output signals, and inverts the output signal from minus to plus when the integrated voltage becomes higher than the reference voltage.

Specifically, the threshold cross point detection circuit 5
After the signals of the threshold crossing points C ₁ and C _{2 from 1} are input to the transistor 50a, when the integrated voltage becomes the reference voltage, that is, the AC voltage waveforms U1 and U2 in FIG. When the positions of the chopper phase angles r ₁ and r ₂ are reached, the output of the comparator 50b is inverted and output from a minus signal to a plus signal. The plus inversion signal continues to the next zero crossing point where the AC voltage waveforms U ₁ and U 2 cross the zero potential line, and is inverted to a minus signal. The DC chopper control circuit 50 includes a variable resistor 50c for setting the reference voltage, and by changing the resistance value of the variable resistor 50c, the threshold cross points C ₁ and C ₂ can be changed. The time t _x is changed to change the reference voltage value to the comparator 50b, and the inversion timing of the output signal of the comparator 50b, that is, the position (timing) of the chopper phase angles r ₁ and r _{2 in} the AC voltage waveform. As a result, the duty ratios t ₁ / T and t ₂ / T of the AC voltage are changed to change the output.

The variable resistor 50c has the operating mechanism 5 thereof.
The resistance value is changed by 0d, and the operation mechanism 50d is operated by a signal from the computer CPU, so that the resistance values for band sending, band primary tightening, and secondary tightening are respectively changed. Is to be changed. By changing the resistance value (reference voltage value) of the variable resistor 50c, the chopper phase angle r ₁ of the AC voltage waveform is continuously changed from 0 ° to 180 ° (180 ° to 360 °). With this change, the duty ratios t ₁ / T and t ₂ / T of the AC voltage can be changed to change the power supply output from 100% to 0.

By setting the resistance value (reference voltage value) of the variable resistor 50c to a specific value, the comparator 50b of the DC chopper control circuit 50 can identify the AC voltage waveforms U1 and U2. The respective signals for making the electric power of the duty ratios t ₁ / T and t ₂ / T are constantly output, and the respective output signals are the AND gate 5
2 is input to the AND gate 52, while signals for transmitting the band secondary tightening, the band primary tightening, and the time for sending the band are respectively input from the computer CPU. ing. Each output signal from the AND gate 52 is input to the solid state relay SSR, and the solid state relay SSR phase-controls the AC voltage waveforms U1 and U2 on the basis of the input signal to specify a specific duty ratio. t
_As electric power of ₁ / T and t ₂ / T, the actuator 45
To supply.

A wiring 62 is connected to the computer CPU from the variable resistor 50c portion of the DC chopper control circuit 50, and an AC voltage having a specific duty ratio supplied to the actuator 45 at the time of secondary tightening is applied. A signal (reference voltage value) corresponding to the output is input to the computer CPU, and the band end for setting the press crimping time at the time of press crimping after heating and melting the overlapping portion of the band B is set. It is used as a signal for driving the stepping motor M ₁ of the processing mechanism K.

A drive signal from the computer CPU to the stepping motor M ₁ of the band edge processing mechanism K is performed by operating a driver D ₁ via a pulse oscillator P _1, and the computer CPU outputs the band. The drive signal to the stepping motor M ₂ of the delivery tightening mechanism S is performed by operating the driver D ₂ via the pulse generator P ₂ .

Next, the operation of the packing machine 10 of this embodiment configured as described above will be described. In the operation of the packing machine 10 of the present embodiment, when the power of a control device (not shown) is turned on, a pool feed motor (not shown)
And stepping motor M ₂ for feed rollers (Fig. 4)
When and are activated and rotated, the leading end of the band B is transferred by the rotational driving force of the pool feed roller 21 and the pressing roller 22, and moves in the passage in the vertical feed opposed band guides 25 and 26. And is guided to the contact portion between the feed roller 30 and the pinch roller 40 of the band delivery tightening mechanism S. The tip portion of the band guided to the contact portion has the feed roller 30 and the pinch roller 4
It will be nipped in the contact portion between 0 and and will be rotatably transferred. When transmitting the band B, a signal is input from the computer CPU to the AND gate 52. Since the signal from the DC chopper control circuit 50 is always input to the AND gate 52, an output signal is output from the AND gate 52. The output signal is input to the solid state relay SSR, and the solid state relay SSR gives electric power having a specific relatively low duty ratio to the solenoid actuator 45. The pinch roller 40 is pressed by the feed roller 30 with a pressing force suitable for band feeding which is not so strong due to the application of the AC voltage having the specified relatively low duty ratio.

The feed roller 30 and the pinch roller 4
As a result of the rotation feeding operation with 0, the tip of the band B is moved to the band end processing mechanism K on the lower surface side of the work table 14.
After passing through the vicinity of the top of the object, the object W to be packed is guided while being guided by the gate-shaped arch portion 15 and is circulated around the object to be packed W in the band end processing mechanism K to detect a feed completion detection switch 63 ( It is sent to the position detected by Fig. 4). When the front end of the band B is detected by the detection switch 63, the stepping motor M ₂ for the feed roller is once stopped to stop the band feeding, and the front end portion of the band B in the band end processing mechanism K is stopped. Then, at a predetermined timing, the stepping motor M ₂ for the feed roller is rotationally driven at a high speed with a low torque in a direction opposite to the direction in which the band B is sent out. Tightening is performed. Upon starting the primary tightening, a signal is output from the computer CPU to the operating mechanism 50d of the variable resistor 50c, and the resistance value of the variable resistor 50c is changed by the operation of the operating mechanism 50d to perform the primary tightening. A signal is input to the AND gate 52 from the computer CPU while the resistance value is set to an appropriate value. Since a signal having a duty ratio suitable for the primary tightening is input from the DC chopper control circuit 50 to the AND gate 52, an output signal is output from the AND gate 52. An output signal from the AND gate 52 is input to the solid-state relay SSR, and the solid-state relay SSR generates AC power having a specific relatively low duty ratio different from that at the time of band transmission, by the solenoid actuator 45.
Be loaded into. The pinch roller 40 is pressed by the feed roller 30 with a certain not so strong pressing force by the load of the AC voltage having the specific relatively low duty ratio.

Then, the band B is subjected to primary tightening.
Is brought into contact with the outer peripheral surface of the article W to be pulled back, and when the tension acting on the band B is suddenly increased, slippage occurs between the band B and the feed roller 30. The speed at which the pinch roller 40 is pulled back and the rotational speed of the pinch roller 40 decrease rapidly. The decrease in the rotation speed is detected by the rotation speed sensor 64 (FIG. 4), and the computer CPU outputs a control signal to complete the primary tightening and start the secondary tightening based on the detection signal.

That is, the stepping motor M ₂ for the feed roller is rotationally driven in the same direction as the primary tightening of the band B with a low speed and high torque, and the secondary tightening of the band B is performed. Upon starting the secondary tightening, a signal is output from the computer CPU to the operating mechanism 50d of the variable resistor 50c, and the operating mechanism 50d is operated.
By changing the resistance value of the variable resistor 50c to a resistance value for secondary tightening different from the primary tightening, the signal is newly output to the AND gate 52. Since the signal from the DC chopper control circuit 50 is always input to the AND gate 52, an output signal is output from the AND gate 52. The output signal from the AND gate 52 is input to the solid state relay SSR,
Due to SR, the AC power having a duty ratio higher than that at the time of the primary tightening causes the solenoid type actuator 45.
Is given to By applying the AC voltage having the specific high duty ratio, the pinch roller 40 causes the feed roller 30 to have a high pressing force adapted to the specific secondary tightening.
Has been pressed.

Then, when the secondary tightening progresses and the tension of the band B further increases rapidly (the limit of the secondary tightening force is reached), slippage occurs between the band B and the feed roller 30. The rotation speed of the pinch roller 40 sharply decreases. The decrease in the rotation speed is detected by the rotation speed sensor 64, and the rotation drive of the stepping motor M ₂ for the feed roller is stopped based on the output signal of the computer CPU.

At the same time as the rotation drive of the stepping motor M ₂ for the feed roller is stopped, the stepping motor M ₁ of the band end processing mechanism S is driven to move the front end and the rear end of the band by a heater or the like. The polymerized portion is melted by heating, and the melted portion is pressure-bonded by a press, cooled and joined, and the rear end of the band B is cut.

In the above operation, the time for pressing the melting portion is determined by the wiring 62 from the reference voltage setting portion of the DC chopper control circuit 50 to the computer CP.
The setting is made by the computer CPU based on the reference voltage signal guided to U, and the stepping motor M ₁ of the band edge processing mechanism K is driven. Thereby, the pressing time of the melted portion corresponding to the secondary tightening force can be set.

As will be understood from FIG. 5, when the control circuit of the control device C of the packing machine 10 of the present embodiment is supplied with different values of the power supply power (AC voltage waveforms U1 and U2), Variable resistor 50 of the DC chopper control circuit 50
Even if the resistance value of c is the same, the threshold crossing point C
The positions of ₁ , C ₂ are the above-mentioned AC voltages (AC voltage waveforms) U1,
Depending on U2, the duty ratio (t ₁ / T, t ₂ / T) is made different, and the AC voltage (AC voltage waveform) U _{2 having} a lower potential is controlled to have a higher duty ratio.

As can be seen from the comparison with the AC voltage waveform diagram of the duty control of the AC voltage based on the control circuit of the conventional packing machine of FIG. 7, in the conventional example, the potential of the AC voltage of the power supply decreases. In the present embodiment, on the contrary, the duty ratio increases as the potential decreases, and the output power increases based on the increase in the duty ratio. As a result, even if the potential of the AC voltage of the power supply decreases, the output does not decrease, or even if it decreases, the decrease can be minimized. By such control, it is possible to minimize the change in the pressing force of the pinch roller against the feed roller even if the voltage of the power supply changes.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and a design can be made without departing from the spirit of the present invention described in the claims. , Various changes can be made. Although the present invention has been described as using only one threshold cross point detection circuit and one DC chopper control circuit, three DC chopper control circuits are arranged in parallel with respect to one threshold cross point detection circuit, Each of the DC chopper control circuits for band secondary tightening, band primary tightening, and
It is also possible to deploy it separately for band transmission. The variable resistor of each DC chopper control circuit, when used for the band primary tightening and the band sending, has a structure in which a specific resistance value (reference voltage value) is preset and incorporated in the DC chopper control circuit. When using it for the secondary tightening, the change operation part is used on the operation panel of the packing machine so that the resistance value (reference voltage value) can be operated and changed from the outside when the packing machine is used. When installed, suitable operation can be performed.

[0048]

As can be understood from the above description, the packaging machine of the present invention is a threshold value for changing the calculation starting point (threshold cross point) of the chopper phase angle r of the DC chopper control circuit based on the voltage fluctuation of the power supply. Since a cross point detection circuit is provided,
Even if the voltage of the power supply changes, the change in the pressing force of the pinch roller against the feed roller can be minimized.

[Brief description of drawings]

FIG. 1 is a schematic front view in which a front side wall is removed to show an internal configuration of an embodiment of a packing machine according to the present invention.

FIG. 2 is an enlarged view of a band delivery tightening mechanism of the packing machine shown in FIG.

3 is a sectional view of the band delivery tightening mechanism of FIG. 2 taken along the line III-III.

FIG. 4 is a diagram showing an example of a control circuit of the packing machine according to the embodiment shown in FIG.

5 is a diagram showing phase control of a voltage supplied to a solenoid actuator of the packing machine according to the embodiment shown in FIG.

FIG. 6 is a diagram showing detection control of threshold cross points of a threshold cross point detection circuit of the control circuit of FIG. 4;

FIG. 7 is a diagram showing phase control of a voltage supplied to a solenoid actuator of a conventional packing machine.

[Explanation of symbols]

10 packing machine 30 the feed rollers 40 pinch roller 45 solenoid actuator 50 DC chopper control circuit 50c variable resistor 51 threshold cross point detection circuit C controller C ₁ threshold cross point C ₂ threshold crossing point CPU computer S-band delivery tensioning mechanism SSR Solid State relay U ₁ supply AC voltage waveform U ₂ supply AC voltage waveform r ₁ chopper phase angle r ₂ chopper phase angle

Claims (2)

[Claims] 1. A packing machine 10 comprising a band delivery tightening mechanism S having a solenoid type actuator 45 for adjusting a pressing force of a pinch roller 40 against a feed roller 30 and a controller C, wherein the controller C supplies a supply AC. Threshold cross point detection circuit 51 that outputs signals of threshold cross points C ₁ and C ₂ of voltage waveforms U ₁ and U ₂ , and supply to solenoid actuator 45 by receiving signals of threshold cross points C ₁ and C _2. A packaging machine comprising: a DC chopper control circuit 50 for phase-controlling an AC voltage; and a solid state relay SSR that operates by receiving a signal from the DC chopper control circuit 50. 2. The DC chopper control circuit 50 includes a variable resistor 50c capable of changing the chopper phase angles r ₁ and r ₂ of the supply AC voltage, and the calculation starting point of the chopper phase angles r ₁ and r ₂ is the above. The packing machine according to claim 1, wherein the packing machine is set based on the threshold cross points C ₁ and C ₂ detected by the threshold cross point detection circuit 51. [0001]