Three-motor synchronous control system for power and free conveying chain

Abstract

The utility model relates to a three-motor synchronous control system for a power and free conveying chain, which comprises an HMI touch screen master controller, a PLC unit, a frequency converter, a motor group and a speed encoder group, the HMI touch screen master controller is connected with the PLC unit through a network, the PLC unit is connected with the frequency converter through a network, and the motor group is connected with the speed encoder group through a network. The frequency converter is connected with the motor set and can adjust the rotating speed of the motor set according to an instruction sent by the PLC unit, the motor set is connected with the power and free conveying chain set and can drive the power and free conveying chain set to operate, and the speed encoder set is connected into the power and free conveying chain set to monitor the speed of the power and free conveying chain set. The speed encoder group is connected with the PLC unit through a network and can feed back speed information to the PLC unit, and the three-motor synchronous control system for the power and free conveying chain is high in operation efficiency, low in control cost and compact in structure.

Description

Technical Field

[0001] The utility model relates to the technical field of industrial automation, and in particular to a three-motor synchronous control system for an accumulation conveyor chain. Background Art

[0002] The accumulation conveyor line is an ideal equipment for continuously conveying articles inside the workshop and between workshops at an ideal speed according to the reasonable process line of users, so as to achieve the ideal operation of an automated or semi-automated assembly line. It can be arranged arbitrarily in three-dimensional space, can play the role of aerial storage, save the ground use area, and the accumulation conveyor chain is widely used in fields such as spraying, drying, surface cleaning, electroplating, assembly, product storage and transmission transfer, etc. due to its advantages of long conveying distance, large operating speed range, flexible turning, climbing and layout. Since some accumulation conveyor lines are very long and there are many accumulated workpieces, it cannot be driven by only one motor and needs to be divided into several parts and driven by two or more motors respectively.

[0003] In the past, when the conveyor chain was divided into several parts, there was a tensioning expansion joint at its boundary. If the speed of the chain in this part was less than that of other parts, the distance of the tensioning expansion joint would be compressed. If the spacing was compressed completely, the chain would accumulate at a certain point and generate redundancy, which would cause the conveyor chain to stop. On the contrary, if the speed of the chain in this part was greater than that of other parts, its spacing would increase. If it exceeded a certain degree, the chain would even be broken. To ensure the normal operation of the conveyor chain, the moving speeds of each part of the conveyor chain must be the same, that is, synchronous operation. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a three-motor synchronous control system for an accumulation conveyor chain with high operating efficiency, low control cost and compact structure in view of the defects of the prior art.

[0005] The utility model is realized by the following technical solutions: A three-motor synchronous control system for an accumulation conveyor chain. In order to realize the synchronous operation of each part of the accumulation conveyor chain, prevent the accumulation or breakage of the accumulation conveyor chain, and improve the operating efficiency of the entire conveying system, the control system includes an HMI touch screen main control, a PLC unit, an inverter, a motor group, and a speed encoder group. The HMI touch screen main control is connected to the PLC unit through a network. The PLC unit is connected to the inverter through a network and is used to send an instruction for controlling the rotation speed to the inverter. The inverter is connected to the motor group and is used to control the rotation speed of the motor. The motor group is connected to the accumulation conveyor chain group and can drive the accumulation conveyor chain group to operate. The speed encoder group is connected to the accumulation conveyor chain group to monitor the speed of the accumulation conveyor chain group. The speed encoder group is connected to the PLC unit through a network and can feedback speed information to the PLC unit.

[0006] Further, to adapt to a longer conveying line, the accumulation conveying chain group includes three mutually connected accumulation conveying chains. Correspondingly, the motor group includes a first motor, a second motor, and a third motor. The three accumulation conveying chains are respectively driven by the first motor, the second motor, and the third motor. The speed encoder group includes a first speed encoder, a second speed encoder, and a third speed encoder. The first speed encoder, the second speed encoder, and the third speed encoder are respectively connected to the three accumulation conveying chains. According to the actual situation, more or fewer mutually connected accumulation conveying chains and corresponding numbers of motor groups and speed encoder groups can also be designed.

[0007] To adjust the tightness of the chain, ensure that the chain always maintains an appropriate tension, and achieve smooth operation, the three-motor synchronous control system for the accumulation conveying chain further includes a set of tension unit limit switches, and the tension unit limit switches are arranged on the tensioning section within the accumulation conveying chain group.

[0008] To improve the service life of the accumulation conveying chain group, a flexible connection is adopted between the motor group and the accumulation conveying chain group.

[0009] The steps of using the three-motor synchronous control system for the accumulation conveying chain to control the operation of the accumulation conveying chain group are as follows:

[0010] Step 1: Press the automatic operation button on the HMI touch screen main control. The PLC unit detects whether the tension unit limit switch acts, and whether the first speed encoder, the second speed encoder, and the third speed encoder, and the frequency converter network communication are normal;

[0011] Step 2: If it is detected in Step 1 that the tension unit limit switch does not act and the network communication is normal, start the first motor, the second motor, and the third motor according to the preset scheme;

[0012] Step 3: The frequency converter and the PLC unit achieve control through network communication. The PLC unit sends control instructions and frequency instructions to the frequency converter. The frequency converter drives the first motor, the second motor, and the third motor to operate at a preset frequency. The first motor, the second motor, and the third motor respectively drive the three accumulation conveying chains to run synchronously. To reduce the impact force, after the motor starts slowly, it runs at a low speed for three seconds first, and then accelerates to the set speed. When the driving force changes exceed the limit due to the asynchronous running speeds of the three accumulation conveying chains resulting in chain accumulation, the connection between the corresponding motor and the sprocket gear of the accumulation conveying chain slips through the clutch plate to balance the driving force. The first speed encoder, the second speed encoder, and the third speed encoder located on the three accumulation conveying chains feedback the real-time speeds of the corresponding accumulation conveying chains to the PLC unit;

[0013] Step 4: If the speed values of the first speed encoder, the second speed encoder, and the third speed encoder feedback corresponding to the accumulation conveyor chain are within the allowable error, continue to run; if outside the allowable error, issue a warning and start timing, continue to run the equipment, and immediately stop when the warning timing exceeds the set protection time;

[0014] Step 5: If the speed values of the first speed encoder, the second speed encoder, and the third speed encoder feedback corresponding to the accumulation conveyor chain are within the allowable error with the speed of the accumulation conveyor chain calculated from the corresponding running pulses, continue to run; if outside the allowable error, issue a warning and start timing, continue to run the equipment, and immediately stop when the warning timing exceeds the set protection time;

[0015] Step 6: Check whether the limit switch of the tensioning unit is normal. If normal, continue to execute Step 4 and Step 5 until the system is shut down; if any one is abnormal, immediately shut down the system.

[0016] The beneficial effects of the present utility model are as follows: By adjusting the speed through the slipping of the clutch plate at the driving part, and monitoring and feedbacking the speed of each section of the conveyor chain, stopping and restarting in time effectively avoid the accumulation or breakage of the conveyor chain, greatly improving the operation efficiency and reducing the control cost; By only setting a set of tensioning joints and corresponding tensioning unit limit switches in the accumulation conveyor chain group, the installation space is reduced, and the compactness of the entire system structure is improved; By optimizing the connection form between the motor group and the accumulation conveyor chain group, the service life of the entire conveying system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the three-motor synchronous control system for the accumulation conveyor chain of the present utility model;

[0018] Figure 2 is the PLC unit control method point diagram of the three-motor synchronous control system for the accumulation conveyor chain of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The following elaborates on the preferred embodiments of the present utility model in detail with reference to the accompanying drawings, so that the advantages and features of the present utility model can be more easily understood by those skilled in the art, thereby making the protection scope of the present utility model more clearly defined.

[0020] Such as Figure 1As shown in the figure, a three-motor synchronous control system for an accumulation conveyor chain of the present utility model includes an HMI touch screen main control, a PLC unit, an inverter, a motor group, a speed encoder group, and a tension unit limit switch. The HMI touch screen main control is connected to the PLC unit through a network. The PLC unit is connected to the inverter through a network. The inverter is connected to the motor group and can adjust the rotation speed of the motor group according to the instructions issued by the PLC unit. The motor group is connected to the accumulation conveyor chain group and can drive the accumulation conveyor chain group to operate. The speed encoder group is connected to the accumulation conveyor chain group to monitor the speed of the accumulation conveyor chain group. The speed encoder group is connected to the PLC unit through a network and can feedback speed information to the PLC unit. The tension unit limit switch is arranged on the tension section in the accumulation conveyor chain group.

[0021] The accumulation conveyor chain group includes three mutually connected accumulation conveyor chains. The motor group includes a first motor M1, a second motor M2, and a third motor M3. The three accumulation conveyor chains are flexibly connected to the first motor M1, the second motor M2, and the third motor M3 and are respectively driven by the first motor M1, the second motor M2, and the third motor M3. The speed encoder group includes a first speed encoder E1, a second speed encoder E2, and a third speed encoder E3. The first speed encoder E1, the second speed encoder E2, and the third speed encoder E3 are respectively connected to the three accumulation conveyor chains.

[0022] The main electrical configuration in this embodiment is as follows: The inverter selects the Siemens G120 7.5KW inverter. The PLC unit selects the Siemens 1511 series (with a 12M memory card). The input module is S7-1500 DI16x24VDC, and the output module is S7-1500 DQ16x24VDC. The speed encoder selects the SICK AFM60A-S4NB018x12 with PN communication. The HMI touch screen main control uses the Siemens KTP700 basic version.

[0023] When the "start" button is pressed on the HMI touch screen main control, the PLC unit decides whether the system can be started and whether to start according to the subroutine based on whether there is an alarm in the system and whether the alarm occurs during operation. If there is no alarm, the three motors start simultaneously, and the accumulation conveyor chain group starts to move. In order to reduce the impact force, after the motors start slowly, they first run at a low speed for three seconds, and then accelerate to the set speed for operation. During the operation, the speed of each section of the accumulation conveyor chain is monitored, and the motor speed is calculated through the running pulses of the corresponding motors. When the difference between the speed of the accumulation conveyor chain and the speed of the accumulation conveyor chain calculated by pulse detection is large, a warning is issued and timed. If the timing exceeds the set time, the machine stops; when the speed difference between the three sections of the accumulation conveyor chain exceeds the limit, a warning is issued and timed. If the timing exceeds the set time, the machine stops.

[0024] The specific steps for using this three-motor synchronous control system for the accumulation conveyor chain to control the operation of the accumulation conveyor chain group are as follows. The PLC unit, the frequency converter, and the motor group achieve control through network communication. The input and output points of the PLC unit are as Figure 2 shown.

[0025] Step 1: Press the automatic operation button on the HMI touch screen main control. The PLC unit detects whether the limit switch of the tensioning unit acts, whether the first speed encoder E1, the second speed encoder E2, and the third speed encoder E3, and whether the network communication of the frequency converter is normal;

[0026] Step 2: If it is detected in Step 1 that the limit switch of the tensioning unit does not act and the network communication is normal, then start the first motor M1, the second motor M2, and the third motor M3 according to the preset scheme;

[0027] Step 3: The frequency converter and the PLC unit achieve control through network communication. The PLC unit sends control instructions and frequency instructions to the frequency converter. The frequency converter drives the first motor M1, the second motor M2, and the third motor M3 to run at the preset frequency. The first motor M1, the second motor M2, and the third motor M3 respectively drive the three sections of the accumulation conveyor chain to run synchronously. After the motor starts slowly, it runs at a low speed for three seconds first, and then accelerates to the set speed. When the driving force changes exceed the limit due to the asynchronous running speed of the three sections of the accumulation conveyor chain resulting in chain accumulation, the connection between the corresponding motor and the chain disc gear of the accumulation conveyor chain slips through the clutch plate to balance the driving force. The first speed encoder E1, the second speed encoder E2, and the third speed encoder E3 located on the three sections of the accumulation conveyor chain feedback the real-time speed of the corresponding section of the accumulation conveyor chain to the PLC unit;

[0028] Step 4: If the speed values of the corresponding accumulation conveyor chain feedback by the first speed encoder E1, the second speed encoder E2, and the third speed encoder E3 are within the allowable error, continue to run; if outside the allowable error, issue a warning and start timing, continue to run the equipment, and immediately stop when the warning timing exceeds the set protection time;

[0029] Step 5: If the speed values of the corresponding accumulation conveyor chain feedback by the first speed encoder E1, the second speed encoder E2, and the third speed encoder E3 are within the allowable error from the speed of the accumulation conveyor chain calculated by the corresponding running pulses, continue to run; if outside the allowable error, issue a warning and start timing, continue to run the equipment, and immediately stop when the warning timing exceeds the set protection time;

[0030] Step 6: Check whether the limit switch of the tensioning unit is normal. If normal, continue to execute Step 4 and Step 5 until the system is shut down; if any one is abnormal, immediately shut down the system.

[0031] The following data can be set on the HMI touch screen main control:

[0032] 1. Set the operating speed (frequency) of the three-stage accumulation conveyor chain;

[0033] 2. Upper and lower limits of the difference between the speed of the accumulation conveyor chain and the motor speed (converted to chain speed);

[0034] 3. Upper and lower limits of the speed difference of the three-stage accumulation conveyor chain.

[0035] The following data can be displayed on the HMI touch screen main control:

[0036] 1. The real-time operating speed (frequency), current, and torque of each motor;

[0037] 2. The real-time operating speed of each motor and the actual speed of each stage of the accumulation conveyor chain;

[0038] 3. The alarm records and system status of the system.

[0039] In all the examples shown and described here, any specific value should be construed as merely exemplary, not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0040] The above-described embodiments merely represent several implementation manners of the present utility model. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the utility model patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all belong to the protection scope of the present utility model.

Claims

1. A three-motor synchronous control system for an accumulation conveyor chain, characterized in that: It includes an HMI touch screen main control, a PLC unit, an inverter, a motor group, and a speed encoder group. The HMI touch screen main control is connected to the PLC unit through a network. The PLC unit is connected to the inverter through a network. The inverter is connected to the motor group and can adjust the rotational speed of the motor group according to the instructions issued by the PLC unit. The motor group is connected to the accumulation conveyor chain group and can drive the accumulation conveyor chain group to operate. The speed encoder group is connected to the accumulation conveyor chain group to monitor the speed of the accumulation conveyor chain group. The speed encoder group is connected to the PLC unit through a network and can feedback speed information to the PLC unit.

2. The three-motor synchronous control system for the accumulation conveyor chain according to claim 1, wherein: It further includes a set of tension unit limit switches, and the tension unit limit switches are arranged on the tension sections within the accumulation conveyor chain group.

3. The three-motor synchronous control system for the accumulation conveyor chain according to claim 1, wherein: The accumulation conveyor chain group includes three sections of accumulation conveyor chains connected to each other. The motor group includes a first motor, a second motor, and a third motor. The three sections of accumulation conveyor chains are respectively driven by the first motor, the second motor, and the third motor. The speed encoder group includes a first speed encoder, a second speed encoder, and a third speed encoder. The first speed encoder, the second speed encoder, and the third speed encoder are respectively connected to the three sections of accumulation conveyor chains.

4. The three-motor synchronous control system for the accumulation conveyor chain according to claim 3, characterized in that: A flexible connection is adopted between the motor group and the accumulation conveyor chain group.

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