Semi-automatic strapping machine control circuit

Abstract

The utility model discloses a semi-automatic strapping machine control circuit, and relates to the technical field of strapping machines. Comprising a main control module and a display operation module. The main control module comprises a first single-chip microcomputer, a power supply circuit, a motor driving circuit, a voltage sampling circuit, a current sampling circuit, a first serial communication interface and an external signal interface circuit. The display operation module comprises a second single-chip microcomputer, a nixie tube display circuit, a key circuit, an indicating lamp circuit and a second serial communication interface. The display operation module displays set parameters and working states through a nixie tube and an indicator lamp, so that the set parameters are completely quantified, and the purpose of accurately setting the parameters is achieved; the temperature gear is limited to be 3 gears by a program, so that the problem that the ironing head is damaged due to unreasonable setting of a user is avoided; the display operation module controlled by the independent single-chip microcomputer is connected with the main control module through the serial communication interface, so that the number of control signal lines is reduced, and the complexity of system wiring is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of strapping machines, and particularly relates to a control circuit for a semi-automatic strapping machine. Background Art

[0002] A strapping machine, also known as a bundling machine, is a device for strapping items with a strapping band. The strapping process of the strapping machine consists of several steps such as tape feeding back, tensioning, bonding, tape cutting, and tape feeding. The common strapping machines on the market at present are divided into two major categories: semi-automatic and fully automatic. At present, the semi-automatic strapping machine adopting the dual-motor scheme is more energy-saving and has a longer service life compared with the traditional single-motor scheme, and has gradually become the mainstream scheme in the industry. In the dual-motor scheme, the main shaft motor is responsible for driving the rotation of the main shaft of the strapping machine core, and combining with the cam structure on the main shaft to realize the corresponding strapping actions; the tape feeding and retracting motor is responsible for tape feeding and retracting and strapping actions.

[0003] At present, the control circuits of common semi-automatic strapping machines on the market basically debug various parameters through potentiometer knobs. Since it is not easy to quantify the adjustment angle of the potentiometer, users cannot accurately adjust the desired parameters during the use process.

[0004] In addition, the current temperature adjustment basically controls the heating power of the hot head by adjusting the conduction angle of the thyristor through a potentiometer. This method has a very large power adjustment range, and it is very easy to cause the temperature of the hot head to be too high due to unreasonable settings of users, which affects the service life of the hot head.

[0005] Thirdly, multiple potentiometers, buttons, indicators, etc. are all connected by independent wires, which also leads to the complex overall wiring of the system and is not convenient for production and processing.

[0006] It can be seen from the above analysis that it is necessary to further optimize and improve the existing control circuit of the strapping machine. Summary of the Invention

[0007] In order to overcome the deficiencies of the prior art, the utility model provides a control circuit for a semi-automatic strapping machine. By using digital tubes and indicators to digitalize the set parameters, the accuracy of parameter setting is improved; and the temperature adjustment is limited within 3 gears, thus avoiding the problem that unreasonable user settings affect the service life of the hot head; in addition, the number of system connections is greatly reduced through a serial communication interface.

[0008] To achieve the above object, the technical solution adopted by the utility model is as follows:

[0009] A control circuit for a semi-automatic strapping machine includes a main control module and a display operation module.

[0010] The main control module includes a first single-chip microcomputer, a power supply circuit, a motor drive circuit, a voltage sampling circuit, a current sampling circuit, a first serial communication interface, and an external signal interface circuit; the power supply circuit supplies power to the main control module; the motor drive circuit is respectively used to drive the spindle motor and the tape feed and retract motor to rotate; the voltage sampling circuit is used to sample the input voltage of the power supply; the current sampling circuit is used to sample the current value in the tape feed and retract motor; the external signal interface circuit is used to obtain external control signals, including a tape insertion signal interface and a cam position signal interface.

[0011] The display and operation module includes a second single-chip microcomputer, a digital tube display circuit, a key circuit, an indicator light circuit, and a second serial communication interface; the key circuit includes a movement operation key and a parameter setting key; the digital tube display circuit and the indicator light circuit are used to display the control parameters and status information of the strapping machine. The movement operation keys usually include a tape feed key and a reset key. If necessary, the functions of the tape feed key and the reset key can also be combined into the same key, that is, when the movement is not in the zero position, it is the reset key, and when the movement is in the zero position, it is the tape feed key. The parameter setting keys can be set in a more flexible way. You can use the setting key to switch and select different parameters, and then use the plus and minus keys to adjust the parameters; you can also use independent parameter setting keys for each parameter, etc.

[0012] The second serial communication interface in the display and operation module is connected to the first serial communication interface in the main control module. Using a serial communication interface can greatly reduce the number of communication cables. Common serial communication protocols include UART, SPI, IIC, CAN, etc.

[0013] Preferably, the control circuit of the semi-automatic strapping machine further includes a heating control circuit, and the heating control circuit is arranged in the main control module or the display and operation module. The heating control circuit has two setting methods. One is to be arranged in the main control module and electrically connected to the first single-chip microcomputer; the other is to be arranged in the display and operation module and electrically connected to the second single-chip microcomputer.

[0014] Preferably, the ratio between the nominal resistance values of the upper-side voltage-dividing resistor and the lower-side voltage-dividing resistor in the voltage sampling circuit is greater than or equal to 7:1 and less than or equal to 13:1.

[0015] Preferably, the current sampling circuit is composed of a sampling resistor and an operational amplifier circuit, and the operational amplifier circuit is integrated inside the first single-chip microcomputer.

[0016] Preferably, a low-pass filter circuit is connected to the output end of the operational amplifier circuit, and the output port of the low-pass filter circuit is connected to the AD sampling pin of the first single-chip microcomputer.

[0017] Preferably, an electromagnetic brake drive circuit is further included in the main control module; the external signal interface circuit further includes a pulse signal interface and a start signal interface.

[0018] Preferably, the indicator light circuit includes an operation status indicator light, a mode selection indicator light, and a temperature gear indicator light.

[0019] Preferably, the mode selection indicator light includes 3 indicator lights corresponding to the three modes of light package, normal, and high speed respectively; the temperature gear indicator light includes 3 indicator lights corresponding to the three temperature gears of low temperature, medium temperature, and high temperature respectively.

[0020] Preferably, the first serial communication interface and the second serial communication interface adopt the UART communication protocol, and the physical layer adopts one of RS232, RS485, and TTL levels.

[0021] Preferably, the power supply circuit in the main control module includes two sets of output power supplies. One set of output power supply voltage is 5V, which is used to supply power to the first single-chip microcomputer and its peripheral circuits; the other set of output power supply voltage is 12V, which is used to supply power to the MOS drive chip.

[0022] Compared with the prior art, the beneficial effects of this application are as follows: The display operation module uses digital tubes and indicator lights to display the set parameters and working status, making the set parameters fully quantified, so as to achieve the purpose of accurately setting parameters; the temperature gear is limited to 3 gears by the program, avoiding the problem of damage to the heating head caused by unreasonable user settings; by adopting a display operation module controlled by an independent single-chip microcomputer and connecting the main control module through a serial communication interface, the number of control signal lines is reduced, and the complexity of the system wiring is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a control circuit of a semi-automatic strapping machine of the present utility model.

[0024] Figure 2 It is a schematic diagram of the power supply circuit of a control circuit of a semi-automatic strapping machine of the present utility model.

[0025] Figure 3 It is a schematic diagram of the voltage sampling circuit of a control circuit of a semi-automatic strapping machine of the present utility model.

[0026] Figure 4 It is a schematic diagram of the motor drive circuit of a control circuit of a semi-automatic strapping machine of the present utility model.

[0027] Figure 5 It is a schematic diagram of the current sampling circuit of a control circuit of a semi-automatic strapping machine of the present utility model.

[0028] Figure 6This is the schematic diagram of the external signal interface circuit of the control circuit of a semi-automatic strapping machine of the present utility model.

[0029] Figure 7 This is the schematic diagram of the heating control circuit of the control circuit of a semi-automatic strapping machine of the present utility model.

[0030] Figure 8 This is the schematic diagram of the electromagnetic brake drive circuit of the control circuit of a semi-automatic strapping machine of the present utility model.

[0031] Figure 9 This is the schematic diagram of the digital tube display circuit and the indicator lamp circuit of the control circuit of a semi-automatic strapping machine of the present utility model.

[0032] Figure 10 This is the schematic diagram of the key circuit of the control circuit of a semi-automatic strapping machine of the present utility model.

[0033] Figure 11 This is the schematic diagram of the communication interface circuit of the control circuit of a semi-automatic strapping machine of the present utility model. Specific embodiments

[0034] Next, in combination with the accompanying drawings and specific embodiments, the cam structure of the strapping machine core of the present utility model will be further described to facilitate a clearer understanding of the technical idea claimed by the present utility model.

[0035] Figure 1 The structural schematic diagram of a control circuit of a semi-automatic strapping machine of the present utility model is shown. It includes a main control module and a display operation module. Among them, the main control module is responsible for the packing action of the strapping machine core, and the display operation module is used to provide an operation interface for the main control module and is responsible for displaying the set parameters and operation buttons.

[0036] Figure 2 The power supply circuit part of the main control module is shown. The DC 24V input power supply VIN is converted into a 12V voltage output through the 12V three-terminal voltage regulator chip U12, and the output terminal of U12 is further converted into a 5V voltage output through the 5V three-terminal voltage regulator chip U11. Among them, the 12V voltage output powers the MOS drive chip EG2131, and the 5V voltage output powers the first single-chip microcomputer and its peripheral circuits.

[0037] Figure 3 It is a voltage sampling circuit. The nominal resistance value of the upper voltage-dividing resistor R6 is 36KΩ, and the nominal resistance value of the lower voltage-dividing resistor R7 is 3.6KΩ. The resistance ratio of the upper and lower voltage-dividing resistors is 10:1. Therefore, the output voltage of the voltage-dividing circuit is VIN / 11.

[0038] The motor drive circuit can drive two motors simultaneously, including a cam motor and a tape feeding and retracting motor. The two motors used here are both brushed DC motors. The cam motor is used to drive the camshaft of the strapping machine core, which is commonly referred to as the M1 motor in the industry, and it has only a single rotation direction during operation. The tape feeding and retracting motor realizes the tape feeding and retracting actions by rotating in the forward and reverse directions of the motor. Therefore, the tape feeding and retracting motor needs to achieve bidirectional rotation, which is commonly referred to as the M2 motor in the industry.

[0039] The motor drive circuit includes a half-bridge circuit for driving the cam motor and a full-bridge circuit for driving the tape feeding and retracting motor, as Figure 4 shown. In this embodiment, the model of the MOS drive chip is EG2131. The positive pole of diode D9 is connected to the VCC pin of MOS drive chip U5, and the negative pole is connected to the VB pin of MOS drive chip U5. Capacitor C12 is connected between the VB pin and the VS pin of MOS drive chip U5. Diode D9 and capacitor C12 provide the turn-on gate voltage for the upper-arm MOS transistor of MOS drive chip U5. The HO pin of MOS drive chip U5 is connected to one end of resistor R25 and the negative pole of diode D19. The other end of resistor R25 and the positive pole of diode D19 are simultaneously connected to the gate of MOS transistor Q5. Similarly, the LO pin of MOS drive chip U5 is connected to one end of resistor R28 and the negative pole of diode D20. The other end of resistor R28 and the positive pole of diode D20 are simultaneously connected to the gate of MOS transistor Q6. The upper-arm MOS transistor Q5 and the lower-arm MOS transistor Q6 form a half-bridge circuit for driving the cam motor.

[0040] Similarly, MOS drive chip U2 drives MOS transistors Q2 and Q4, and MOS drive chip U3 drives MOS transistors Q1 and Q3 to form a full-bridge circuit for driving the tape feeding and retracting motor to rotate forward and backward. One end of current sampling resistor R19 is connected to the sources of the two lower-arm MOS transistors Q3 and Q4 in the full-bridge circuit. The other end of current sampling circuit R19 is connected to the negative pole of the power supply.

[0041] As Figure 5 shown, the current sampling circuit has one end of current sampling resistor R19 connected to resistor R2 and the other end connected to resistor R4. The other end of resistor R2 is connected to the OP-P pin of the operational amplifier, and the other end of resistor R4 is connected to the OP-N pin of the operational amplifier. Capacitor C1 is connected between the OP-P and OP-N pins of the operational amplifier. Resistors R2 and R4 and capacitor C1 form a low-pass filter circuit. The OP-O pin of the operational amplifier is connected to resistor R18, and the other side of resistor R18 is connected to capacitor C7 and is simultaneously connected to the AD sampling pin of the first single-chip microcomputer. Capacitor C7 and resistor R18 form a second-stage low-pass filter circuit.

[0042] In this embodiment, the operational amplifier module and the peripheral resistors for setting the amplification ratio are integrated inside the first single-chip microcomputer, which can simplify the circuit structure. In design, it is entirely possible to set an independent operational amplifier chip externally to achieve the same function.

[0043] As Figure 6 shown, the external switch signal is transmitted to the IO pin of the first single-chip microcomputer after being isolated by the optocoupler PC817. The external signal interface in the main control module includes a cam position signal interface, a tape insertion signal interface, a pulse signal interface, and a start signal interface. The main control module controls the bundling machine to complete the bundling action according to the signals provided by the above interfaces.

[0044] This embodiment also includes a heating control circuit, which is arranged in the main control module and is electrically connected to the first single-chip microcomputer. Figure 7 shows the schematic diagram of the heating control circuit. The output pin of the thyristor optocoupler U6 is connected to the thyristor T7 through the resistor R49. The resistor R50 and the capacitor C13 are connected in series between the two main electrodes T1 and T2 of the thyristor. The varistor RV1 is also connected in parallel between the two main electrodes T1 and T2 of the thyristor.

[0045] In this embodiment, an AC heating iron is adopted, so a bidirectional thyristor is selected as the control element for the iron. If the power supply for the iron is changed to a DC power supply, control elements such as MOS transistors and triodes can be used instead.

[0046] Figure 8 shows the schematic diagram of the electromagnetic brake drive circuit. The collector of the output terminal of the optocoupler U4 is connected to the 12V power supply through the resistor R15, and the emitter is connected to the gate of the MOS transistor Q7. The positive electrode of the Schottky diode D25 is connected to the drain of the MOS transistor Q7, and the negative electrode is connected to the power supply VIN, serving as a freewheeling diode.

[0047] The first single-chip microcomputer in the main control module obtains the current state and control signals of the bundling machine core through a voltage sampling circuit, a current sampling circuit, an external signal interface circuit, etc., and then the motor drive circuit, the electromagnetic brake drive circuit, and the heating control circuit perform corresponding actions.

[0048] Figure 9 shows the schematic diagrams of the digital tube display circuit and the indicator lamp circuit in the display operation module. In this example, a common cathode digital tube is used. The 8-segment pins of the digital tube are respectively connected to the IO pins of the second single-chip microcomputer through 8 resistors; the common terminal of the digital tube is connected to the output pin of the Darlington drive chip U1. The light-emitting diodes D2, D3, and D4 respectively correspond to three working modes: light package mode, normal mode, and high-speed mode; the light-emitting diodes D5, D6, and D7 respectively correspond to three temperature ranges: low temperature, medium temperature, and high temperature.

[0049] Figure 10As shown in the schematic diagram of the key circuit, in this embodiment, 7 keys are provided, including 2 movement operation keys and 5 parameter setting keys. The 2 movement operation keys are the tape feeding key and the reset key respectively; the 5 parameter setting keys include the setting key, the parameter increment key, the parameter decrement key, the mode switching key and the temperature switching key. The circuits of the 7 keys are the same, and the key S1 is taken as an example for illustration here. One of the pins of the key S1 is connected to the IO pin of the second single-chip microcomputer, and a resistor R11 is provided on this pin as a pull-up resistor. At the same time, the other end of the key S1 is connected to the system ground.

[0050] In the present utility model, both the first serial communication interface and the second serial communication interface adopt the UART communication protocol, and the physical layer uses the RS485 level for communication. Here, it is also possible to select the RS232 level or directly use the TTL level as needed, and the same purpose can be achieved. The main difference lies in the differences in anti-interference ability and cost of different levels. As Figure 11 shown in the schematic diagram of the RS485 communication interface circuit, in this embodiment, both the first serial communication interface and the second serial communication interface adopt the same circuit structure. Since the master control module and the display operation module adopt the UART serial communication mode, only 2 power supply lines and 2 communication lines, a total of 4 wires, are required for the connection between the two, thus greatly simplifying the overall wiring of the system.

[0051] For those skilled in the art, various corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all these changes and deformations should fall within the protection scope of the claims of the present utility model.

Claims

1. A control circuit for a semi-automatic strapping machine, characterized in that, Including: The main control module and the display operation module; The main control module includes a first single-chip microcomputer, a power supply circuit, a motor drive circuit, a voltage sampling circuit, a current sampling circuit, a first serial communication interface, and an external signal interface circuit; The power supply circuit supplies power to the main control module; The motor drive circuit is respectively used to drive the main shaft motor and the tape feeding and retracting motor to rotate; The voltage sampling circuit is used to sample the power input voltage; The current sampling circuit is used to sample the current value in the tape feeding and retracting motor; The external signal interface circuit is used to obtain external control signals, including a tape insertion signal interface and a cam position signal interface; The display operation module includes a second single-chip microcomputer, a digital tube display circuit, a key circuit, an indicator light circuit, and a second serial communication interface; The key circuit includes a movement operation key and a parameter setting key; The digital tube display circuit and the indicator light circuit are used to display the control parameters and status information of the strapping machine; The second serial communication interface in the display operation module is connected to the first serial communication interface in the main control module.

2. The control circuit of a semi-automatic strapping machine according to claim 1, characterized in that, The semi-automatic strapping machine control circuit further includes a heating control circuit, and the heating control circuit is arranged in the main control module or the display operation module.

3. The control circuit of a semi-automatic strapping machine according to claim 1, characterized in that, The ratio between the nominal resistance values of the upper voltage dividing resistor and the lower voltage dividing resistor in the voltage sampling circuit is greater than or equal to 7:1 and less than or equal to 13:

1.

4. The control circuit of a semi-automatic strapping machine according to claim 1, characterized in that, The current sampling circuit is composed of a sampling resistor and an operational amplifier circuit, and the operational amplifier circuit is integrated inside the first single-chip microcomputer.

5. The control circuit of a semi-automatic strapping machine according to claim 4, characterized in that, A low-pass filter circuit is connected to the output end of the operational amplifier circuit, and the output port of the low-pass filter circuit is connected to the AD sampling pin of the first single-chip microcomputer.

6. The control circuit of a semi-automatic strapping machine according to claim 1, characterized in that, The main control module further includes an electromagnetic brake drive circuit; the external signal interface circuit further includes a pulse signal interface and a start signal interface.

7. The control circuit of a semi-automatic strapping machine according to claim 1, characterized in that The indicator light circuit includes an operation status indicator light, a mode selection indicator light, and a temperature gear indicator light.

8. The control circuit of a semi-automatic strapping machine according to claim 7, characterized in that, The mode selection indicator light includes 3 indicator lights corresponding to three modes of light package, normal, and high speed; the temperature gear indicator light includes 3 indicator lights corresponding to three temperature gears of low temperature, medium temperature, and high temperature.

9. The control circuit of a semi-automatic strapping machine according to claim 1, characterized in that, The first serial communication interface and the second serial communication interface adopt the UART communication protocol, and the physical layer adopts one of RS232, RS485, and TTL levels.

10. The control circuit of a semi-automatic strapping machine according to claim 1, characterized in that, The power supply circuit in the main control module includes two groups of output power supplies. One group of output power supply voltage is 5V, which is used to supply power to the first single-chip microcomputer and its peripheral circuits; the other group of output power supply voltage is 12V, which is used to supply power to the MOS drive chip.

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