Tablet weight automatic control system based on tablet candy production

Abstract

The invention relates to the technical field, and discloses a tablet weight automatic control system based on tablet candy production, comprising: a pressure detection module for detecting the actual pressure value of a candy tablet in real time in the tabletting process; the signal conversion module is used for converting the analog quantity signal output by the pressure detection module into a VME digital signal; the control processing module is used for executing a discretization PID control algorithm, comparing the actual pressure value with a set pressure value and outputting a control instruction; the filling adjusting module is used for adjusting the material filling amount according to the control instruction; the metering guide rail module is used for accurately controlling the material feeding position; vME bus high-speed data transmission (40MB / s) and a PID real-time control algorithm are adopted, the system response time is shortened to be within 100 ms, and compared with 3-5 min response time of a traditional method, the response time is improved by 1800-3000 times. Adjustment can be completed within three tabletting periods after deviation is detected, and generation of unqualified products is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of tablet weight automatic control systems, and more particularly to a tablet weight automatic control system based on tablet candy production. Background Art

[0002] Compressed candies are a common confectionery product, made by pressing ingredients such as powdered sugar into a compacted form under high pressure. During the production process, consistent tablet weight is a key factor affecting product quality, directly impacting the product's appearance, taste, solubility, and consumer acceptance.

[0003] Traditional tablet candy production equipment primarily uses a mechanical tablet weight control method, which involves adjusting the filler's mechanical structure to control the material filling amount, and thus the weight of the candy tablets. However, this method has the following technical issues: Low control accuracy: Traditional mechanical control relies on manual adjustments based on operator experience, making it difficult to achieve precise quantitative control. In actual production, tablet weight deviations typically fall within a range of ±5-8mg, making it difficult to meet the requirements for high-quality candy production.

[0004] Slow response: When raw material characteristics change (such as moisture or particle size distribution), traditional control methods take a long time to detect and adjust, resulting in a large number of substandard products. Statistics show that traditional adjustment response times typically range from 3 to 5 minutes, potentially resulting in thousands of substandard products.

[0005] Lack of real-time monitoring capabilities: Traditional production lines are unable to detect the weight of each candy piece in real time and can only perform quality control through batch sampling, which makes it impossible to detect and correct production deviations in a timely manner.

[0006] High dependence on manual labor: System adjustment is completely dependent on the skill level and experience of the operator. The adjustment effects of different operators vary greatly and are easily affected by human factors, resulting in unstable product quality.

[0007] High energy consumption and scrap rate: Due to insufficient control accuracy, a large amount of overweight or underweight scrap will be generated during the production process. The scrap rate is usually 2-5%, which not only increases production costs but also causes waste of raw materials.

[0008] While some companies have attempted to use weight sensors for post-process testing, this method only works after the candy tablets are pressed, preventing real-time adjustments during the pressing process and resulting in lag. Furthermore, some devices use simple pressure detection, but lack a precise mathematical model linking pressure and tablet weight, making it impossible to establish an effective closed-loop control system.

[0009] Therefore, there is an urgent need to develop a tablet weight control system that can achieve high-precision, real-time, and automated control to solve the above-mentioned technical problems existing in the production of traditional compressed candies. Summary of the Invention

[0010] In order to overcome the above-mentioned defects of the prior art, the present invention provides an automatic tablet weight control system based on tablet candy production to solve the problems existing in the above-mentioned background technology.

[0011] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: an automatic tablet weight control system for tabletted candy production, comprising: a pressure detection module for real-time detection of the actual pressure value to which the candy tablets are subjected during the tableting process; a signal conversion module for converting the analog signal output by the pressure detection module into a VME digital signal; a control processing module for executing a discretized PID control algorithm, comparing the actual pressure value with a set pressure value and outputting a control instruction; a filling adjustment module for adjusting the material filling amount according to the control instruction; a metering guide module for precisely controlling the material delivery position; and a human-computer interaction module for setting target parameters and displaying system status. The modules communicate data via a VME bus to form a closed-loop control system.

[0012] Furthermore, the pressure detection module includes a pressure sensor, a signal conditioning circuit and a filtering circuit. The pressure sensor adopts a strain gauge pressure sensor and is installed at the upper pressing wheel position of the tablet press. The filtering circuit adopts a second-order low-pass filter for signal filtering processing.

[0013] Furthermore, the signal conversion module includes an A / D converter and a VME interface circuit. The A / D converter uses a 16-bit high-precision A / D conversion chip. The data transmission rate of the VME interface circuit is 40MB / s, ensuring the real-time requirements of the system.

[0014] Furthermore, the control processing module includes a VME control computer, a control algorithm unit and a parameter setting unit. The discretized PID control equation executed by the control algorithm unit is: in, For the Control output at each sampling moment; and Respectively and Pressure deviation at each sampling moment; is the sampling period, which is 0.02s here; 、 、 are proportional, integral, and differential coefficients respectively; is the summation operator.

[0015] Furthermore, the control algorithm unit also adopts an integral separation algorithm to prevent integral saturation. When the absolute value of the pressure deviation is greater than or equal to the integral separation threshold, the integral item output is kept unchanged. When the absolute value of the pressure deviation is less than the integral separation threshold, the integral item output is calculated normally.

[0016] Furthermore, the filling adjustment module includes a stepper motor, a reducer, a screw transmission mechanism and a position feedback sensor. The stepper motor adopts a two-phase hybrid stepper motor, the reducer adopts a 1:50 planetary reducer, and the position feedback sensor adopts an incremental encoder.

[0017] Furthermore, the system establishes a pressure-tablet weight conversion function: in, is the weight of the candy piece; is the pressure-tablet weight conversion function; To suppress pressure; is the pressure wheel spacing; is the material density; is the effective area of ​​the punch; is the compression coefficient related to the spacing between the rollers; is the base weight offset.

[0018] Furthermore, the control accuracy parameters of the system are: pressure control accuracy ±0.5kN, tablet weight control accuracy ±2mg, system response time ≤100ms, control cycle 20ms, and pressure setting range 5-95kN.

[0019] Technical effects and advantages of the present invention: 1. Significantly improve control accuracy The present invention establishes an accurate pressure-tablet weight mathematical model: A quantitative description of the relationship between pressure and tablet weight is achieved. Combined with a high-precision pressure sensor (measurement accuracy ±0.1% FS) and a 16-bit A / D converter, the tablet weight control accuracy reaches ±2mg, which is 60-75% higher than the traditional method of ±5-8mg.

[0020] 2. Achieve rapid response control By utilizing VME bus high-speed data transmission (40MB / s) and a PID real-time control algorithm, system response time is reduced to less than 100ms, a 1,800-3,000-fold improvement compared to the 3-5 minute response time of traditional methods. Adjustments can be made within three tableting cycles after detecting a deviation, significantly reducing the number of defective products.

[0021] 3. Establish a complete closed-loop control system By integrating modules such as pressure detection, signal conversion, algorithm control, and filling adjustment, a complete closed-loop control system has been constructed. The system can detect the pressing pressure of each candy piece in real time, calculate the actual piece weight using a pressure-piece weight conversion model, and automatically adjust the filling amount, achieving true real-time automatic control.

[0022] 4. Significantly reduce scrap rate and production costs Verified in actual production, this invention reduces the scrap rate from the traditional 2-5% to below 0.5%, a reduction of over 75%. Based on an annual production capacity of 1,000 tons of pressed candy, this can reduce scrap by 20-45 tons, directly saving 150,000 to 300,000 yuan in raw material costs.

[0023] 5. Eliminate manual dependence and improve production stability The system utilizes fully automatic control, eliminating the need for manual adjustments by operators and eliminating the impact of human factors on product quality. Standardized control parameter settings ensure consistent production across shifts and operators, significantly improving product quality stability.

[0024] 6. Enhance system reliability and intelligence The system features a comprehensive exception handling mechanism, including automatic switching for sensor failures, automatic shutdown for over-limit situations, and extreme position protection, ensuring production safety. Furthermore, the human-machine interaction module provides an intuitive interface for parameter settings and status display, enhancing the intelligence of the equipment.

[0025] 7. Strong adaptability and good scalability The present invention adopts a modular design, and the pressure-to-tablet weight conversion parameters can be adjusted according to different candy recipes, making it suitable for the production of various specifications and types of compressed candies. The open architecture of the VME bus facilitates subsequent function expansion and system upgrades.

[0026] 8. Improve production efficiency and product competitiveness Through precise tablet weight control, product appearance consistency and quality stability are significantly improved, enhancing the product's market competitiveness. At the same time, it reduces quality inspection and rework steps, improving overall production efficiency by approximately 15-20%.

[0027] In summary, the present invention not only technically solves the key problems of low tablet weight control precision, slow response speed, and strong dependence on manual labor in the production of traditional compressed candies, but also achieves multiple advantages in terms of economic benefits, such as cost reduction, efficiency improvement, and product quality improvement. It has significant practical value and promotion prospects. DETAILED DESCRIPTION

[0028] The technical solutions of the present invention will be described clearly and completely below. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The tablet weight automatic control system for tablet candy production involved in the present invention is not limited to the various structures described in the following embodiments. All other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0029] 1. Overall system architecture The tablet weight automatic control system based on tablet candy production includes: a pressure detection module, a signal conversion module, a control processing module, a filling adjustment module, a metering guide module and a human-computer interaction module.

[0030] The pressure detection module is used to detect in real time the actual pressure value PV exerted on each candy tablet during the tableting process; the signal conversion module is used to convert the analog signal output by the pressure detection module into a VME digital signal; the control processing module is used to execute the tablet weight control algorithm, compare the actual pressure value PV with the set pressure value SP and output a control instruction; the filling adjustment module is used to adjust the material filling amount according to the control instruction; the metering guide module is used to accurately control the material delivery position; and the human-computer interaction module is used to set target parameters and display the system status.

[0031] Each module communicates data via the VME bus to form a closed-loop control system, which enables automatic control of tablet weight during the tablet candy production process.

[0032] 2. Detailed description of key modules Pressure detection module The pressure detection module includes a pressure sensor, a signal conditioning circuit and a filtering circuit.

[0033] The pressure sensor, a strain gauge pressure sensor, is installed on the upper roller of the tablet press to monitor the pressure applied to each candy tablet during the pressing process. The sensor has a measurement range of 0-100 kN, an accuracy of ±0.1% FS, and a response time of less than 1 ms.

[0034] The signal conditioning circuit amplifies and linearizes the weak electrical signal output by the pressure sensor, amplifying the 0-10mV signal output by the sensor into a standard 0-10V analog signal. .

[0035] The filtering circuit uses a second-order low-pass filter with a cut-off frequency of 50Hz to filter out high-frequency interference signals. The filtering algorithm is: in, is the filtered pressure signal, 、 、 、 、 are filter coefficients, , , , , is the filter coefficient; 、 、 is the pressure signal at the current, previous and previous two sampling moments; 、 is the filtering result of the previous and the previous two sampling moments.

[0036] Signal conversion module The signal conversion module includes an A / D converter and a VME interface circuit.

[0037] The A / D converter uses a 16-bit high-precision A / D conversion chip to convert the analog signal Converted into digital signal. The conversion relationship is: in, is the converted digital pressure value; is the filtered analog pressure signal; is the minimum value of the analog signal, ; is the maximum value of the analog signal, .

[0038] The relationship between digital pressure value and actual pressure value is: in, is the actual pressure value (kN), $P_{range} P_{offset} D_{pressure}$ is the digital pressure value.

[0039] The VME interface circuit converts the digital pressure value The data is transmitted to the control processing module via the VME bus, which has a transmission rate of 40MB / s to ensure real-time performance.

[0040] Control processing module The control processing module includes a VME control computer, a control algorithm unit and a parameter setting unit.

[0041] The VME control computer adopts a VME single-board computer based on a Pentium processor, runs a real-time operating system, and is responsible for the coordinated control of the entire system.

[0042] The control algorithm unit executes a discretized PID control algorithm, and the discretized control equation is: in, For the Control output at each sampling moment; and Respectively and Pressure deviation at each sampling moment; is the sampling period, which is 0.02s here; 、 、 are proportional, integral, and differential coefficients respectively; is the summation operator.

[0043] In order to prevent integral saturation, the integral separation algorithm is used: in, and Respectively and The integral term output at each sampling moment; is the integral separation threshold; It is a conditional judgment operator.

[0044] In order to establish a quantitative relationship between pressure and tablet weight, a modified pressure-tablet weight conversion function is defined: in, is the weight of the candy piece; is the pressure-tablet weight conversion function; To suppress pressure; is the pressure wheel spacing; is the material density; is the effective area of ​​the punch; is the compression coefficient related to the spacing between the rollers; is the base weight offset.

[0045] The relationship between the compression coefficient and the spacing between the rollers is: in, is the compression coefficient related to the spacing between the rollers; is the pressure wheel spacing; is the coefficient of the zero-order term; is the coefficient of the first-order term; is the coefficient of the quadratic term.

[0046] Typical parameters are: , , .

[0047] The parameter setting unit 33 is used to set PID parameters and pressure-tablet weight conversion parameters. Typical parameter settings are: , , .

[0048] Filling adjustment module The filling adjustment module includes a stepping motor, a reducer, a screw transmission mechanism and a position feedback sensor.

[0049] The stepper motor adopts a two-phase hybrid stepper motor with a step angle of 1.8°, and receives control instructions output by the control processing module through a driver.

[0050] Control output The relationship converted to the stepper motor rotation angle is: in, and Respectively and The cumulative rotation angle of the motor at each sampling moment (°), is the conversion factor.

[0051] The reducer adopts a 1:50 planetary reducer to improve the adjustment accuracy.

[0052] The screw drive mechanism converts rotational motion into linear motion to adjust the filling depth of the filler. The relationship between the filling amount change and the motor rotation angle is: in, For single-step filling volume changes, is the screw lead, is the reduction ratio, is the effective area of ​​the filler.

[0053] The position feedback sensor uses an incremental encoder with a resolution of 1000 pulses / revolution to achieve closed-loop position control.

[0054] Metering rail module The metering guide rail module includes a synchronous motor, a guide rail transmission system and a position control system.

[0055] The synchronous motor is a permanent magnet synchronous motor with a rated power of 1.5kW. It uses a servo drive to achieve precise position control. The motor has a control accuracy of ±0.01mm and a maximum movement speed of 200mm / s.

[0056] The guide rail transmission system adopts a precision ball screw pair with a lead of 5mm and a repeat positioning accuracy of ±0.005mm.

[0057] The position control system uses grating scale feedback with a resolution of 1 μm to ensure the precise positioning of the metering guide rail.

[0058] 3. Control Flow Implementation System initialization process After the system starts, it first enters manual mode and performs the following initialization steps: Step S101: The system performs a self-test after powering on, checking the communication status of each module and the working status of the sensor; Step S102: Reading the system parameter configuration file, including PID parameters, pressure-tablet weight conversion parameters, etc.; Step S103: resetting the filling adjustment module and the metering guide rail module to their initial positions; Step S104 : waiting for the operator to input a set pressure value SP through the human-computer interaction module 6 .

[0059] Automatic control process After the system enters automatic mode, follow the steps below to perform closed-loop control: Step S201: The pressure detection module detects the actual pressure and outputs a filtered pressure signal ; Step S202: The signal conversion module converts Convert to actual pressure value , the conversion time does not exceed 100μs; Step S203: The control processing module calculates the pressure deviation: ; Step S204: Determine whether the deviation is within the allowable range. ,in is the pressure control accuracy threshold: like , the system maintains the current state and goes to step S201 to continue monitoring; like , execute step S205 to adjust the pressure.

[0060] Step S205: The control algorithm unit calculates the control output according to the discretized PID control equation ; Step S206: Control output Convert to stepper motor angle , sent to the filling adjustment module; Step S207: The filling adjustment module 4 performs filling amount adjustment , the adjustment time does not exceed 50ms; Step S208: After waiting for three tableting cycles, the process returns to step S201 to form a closed-loop control.

[0061] Exception handling process Exception handling during system operation includes: Step S301: When a sensor failure is detected, the system automatically switches to a backup sensor and issues a fault alarm; Step S302: When the pressure deviation exceeds the set range for 10 consecutive cycles, the system automatically shuts down and issues an alarm; Step S303: When the filling adjustment module reaches the adjustment limit position, the system pauses the adjustment and prompts to replace the material.

[0062] 4. Specific parameter settings System control parameters Pressure control accuracy: ±0.5kN Tablet weight control accuracy: ±2mg System response time: ≤100ms Control cycle: 20ms Maximum pressure setting range: 5-95kN PID control parameters According to the system identification results, the PID controller parameters are set as follows: Proportional coefficient Integration coefficient differential coefficient Integral limit: ±10 Output limit: ±100 Integration separation threshold: Pressure-tablet weight conversion parameters For a typical candy recipe, the conversion parameters are set as follows: Punch area (11mm diameter round punch) Compression coefficient parameters: , , Material density Basic weight Conversion relationship verification: When pressure , pressure wheel spacing Calculate the tablet weight , and the deviation from the actual measured value is less than ±2%.

[0063] Filling adjustment parameters Filling volume adjustment range: ±20% Single step adjustment amount: 0.5mg Maximum adjustment speed: 100mg / s Control output conversion coefficient: Screw lead reduction ratio Communication interface parameters VME bus clock frequency: 40MHz Data transfer rate: 40MB / s Address space: 32 bits Data width: 16 bits Communication protocol: VME64 standard Through the implementation of the above-mentioned technical solution, the present invention achieves high-precision automatic control of tablet weight during the production of compressed candies. The system can adjust the filling volume in real time based on pressure detection results, ensuring that the weight of each candy tablet is within a set range, thereby improving product quality consistency and production efficiency. In actual production, tablet weight control accuracy has reached ±2mg, and the scrap rate has been reduced to below 0.5%, significantly improving the production quality of compressed candies.

[0064] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An automatic tablet weight control system for tablet candy production, characterized in that: include: The pressure detection module is used to detect the actual pressure value of the candy tablets during the tableting process in real time; A signal conversion module is used to convert the analog signal output by the pressure detection module into a VME digital signal; a control processing module is used to execute a discrete PID control algorithm, compare the actual pressure value with the set pressure value and output a control instruction; a filling adjustment module is used to adjust the material filling amount according to the control instruction; The metering guide module is used to accurately control the material placement position; the human-computer interaction module is used to set target parameters and display system status; each module communicates data through the VME bus to form a closed-loop control system.

2. The tablet weight automatic control system based on tablet candy production according to claim 1, characterized in that: The pressure detection module includes a pressure sensor, a signal conditioning circuit and a filtering circuit. The pressure sensor is a strain gauge pressure sensor installed on the upper pressing wheel of the tablet press. The filtering circuit uses a second-order low-pass filter to perform signal filtering processing.

3. The tablet weight automatic control system based on tablet candy production according to claim 1, characterized in that: The signal conversion module includes an A / D converter and a VME interface circuit. The A / D converter uses a 16-bit high-precision A / D conversion chip. The data transmission rate of the VME interface circuit is 40MB / s, ensuring the real-time requirements of the system.

4. The tablet weight automatic control system based on tablet candy production according to claim 1, characterized in that: The control processing module includes a VME control computer, a control algorithm unit and a parameter setting unit. The discretized PID control equation executed by the control algorithm unit is: in, For the Control output at each sampling moment; and Respectively and Pressure deviation at each sampling moment; is the sampling period, which is 0.02s here; 、 、 are proportional, integral, and differential coefficients respectively; is the summation operator.

5. The tablet weight automatic control system based on tablet candy production according to claim 4, characterized in that: The control algorithm unit also uses an integral separation algorithm to prevent integral saturation. When the absolute value of the pressure deviation is greater than or equal to the integral separation threshold, the integral item output remains unchanged. When the absolute value of the pressure deviation is less than the integral separation threshold, the integral item output is calculated normally.

6. The tablet weight automatic control system based on tablet candy production according to claim 1, characterized in that: The filling adjustment module includes a stepper motor, a reducer, a screw transmission mechanism and a position feedback sensor. The stepper motor adopts a two-phase hybrid stepper motor, the reducer adopts a 1:50 planetary reducer, and the position feedback sensor adopts an incremental encoder.

7. The tablet weight automatic control system based on tablet candy production according to claim 1, characterized in that: The system establishes a pressure-tablet weight conversion function: in, is the weight of the candy piece; is the pressure-tablet weight conversion function; To suppress pressure; is the pressure wheel spacing; is the material density; is the effective area of ​​the punch; is the compression coefficient related to the spacing between the rollers; is the base weight offset.

8. The tablet weight automatic control system based on tablet candy production according to claim 1, characterized in that: The control accuracy parameters of the system are: pressure control accuracy ±0.5kN, tablet weight control accuracy ±2mg, system response time ≤100ms, control cycle 20ms, and pressure setting range 5-95kN.

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