Transformer silicon steel sheet punching stress eliminating method and stress eliminating heater

Abstract

The invention discloses a transformer silicon steel sheet punching stress eliminating method and a stress eliminating heater. The method comprises the steps that a program is initialized; a mechanical arm is controlled to grab the silicon steel sheets, the grabbed silicon steel sheets are placed in a stress relief heater in a spaced and stacked mode, the stress relief heater is controlled to gradually increase the heating temperature according to the heating steps, and the heating temperature continues to the target time on each heating step; obtaining the initial length of the silicon steel sheet and the length variation of the silicon steel sheet in each heating step, and calculating the thermal stress coefficient of the silicon steel sheet by combining the temperature gradient data; and when the thermal stress coefficient of the silicon steel sheets reaches a target value, controlling a punching drill bit to extend into the stress relief heater from the outside of the stress relief heater from top to bottom, and punching the stacked silicon steel sheets one by one. According to the technical scheme, automation and programming of the whole stress relieving process are achieved, and the production efficiency and the operation precision are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of punching silicon steel sheets for transformers, and particularly relates to a method for eliminating punching stress of silicon steel sheets for transformers and a stress elimination heater. Background Art

[0002] In the process of transformer manufacturing, the punching process of silicon steel sheets is one of the key links. The traditional method of punching silicon steel sheets is usually carried out directly in the cold state, and there are many problems with this method. First of all, cold punching will generate large mechanical stresses inside the silicon steel sheets, and these stresses may cause damage to the microstructure of the material, thereby affecting the performance and service life of the transformer. Secondly, due to the high hardness of the silicon steel sheets in the cold state, problems such as severe tool wear and difficulty in ensuring machining accuracy are likely to occur during the punching process, increasing the production cost and the defective rate. In addition, the traditional method cannot effectively eliminate the stresses generated during the punching process, resulting in possible deformation or cracking of the silicon steel sheets during subsequent use, affecting the overall performance of the transformer.

[0003] In recent years, although there have been studies attempting to improve the punching effect of silicon steel sheets through preheating and other methods, most of these methods lack precise temperature control and stress monitoring, and it is difficult to fundamentally solve the impact of punching stress on the performance of silicon steel sheets. Therefore, there is an urgent need in the existing technology for a method and equipment for punching silicon steel sheets that can effectively eliminate punching stress, improve machining accuracy, and increase production efficiency. Summary of the Invention

[0004] The purpose of the present invention is to address the problems existing in the prior art and provide a method for eliminating punching stress of silicon steel sheets for transformers and a stress elimination heater.

[0005] Based on the description of the specification, on the one hand, the present invention provides a method for eliminating punching stress of silicon steel sheets for transformers, including:

[0006] Program initialization;

[0007] Controlling the robotic arm to grasp the silicon steel sheets and placing the grasped silicon steel sheets into the stress elimination heater in a spaced stacked manner, controlling the stress elimination heater to gradually increase the heating temperature step by step according to the heating steps, and maintaining for the target time at each heating step;

[0008] Obtaining the initial length of the silicon steel sheets and the length change amount of the silicon steel sheets at each heating step, and calculating the thermal stress coefficient of the silicon steel sheets in combination with the temperature gradient data;

[0009] When the thermal stress coefficient of the silicon steel sheets reaches the target value, controlling the punching drill to extend from the outside of the stress elimination heater into the inside of the stress elimination heater from top to bottom, and punching the stacked silicon steel sheets one by one;

[0010] Control the punching drill to lift until it disengages from the stress relief heater, control the stress relief heater to lower the temperature to the annealing temperature, and continue for the stress relief time period, and then control the robotic arm to take out the silicon steel sheet.

[0011] In the above technical solution, the entire stress relief process is automated and programmed, improving production efficiency and operation accuracy. The robotic arm is controlled to place the silicon steel sheets into the stress relief heater in an interval stacking manner, and the heating temperature is gradually increased step by step according to the heating steps to ensure uniform heating of the silicon steel sheets, reducing the generation of thermal stress. By real-time monitoring the length change of the silicon steel sheet and combining the temperature gradient data, the thermal stress coefficient of the silicon steel sheet is calculated, providing accurate data support for subsequent punching operations. By heating the silicon steel sheet, the silicon steel sheet is softened, significantly reducing the stress of the silicon steel sheet itself. Then, a drill is used to punch the silicon steel sheet at this time. When the softened silicon steel sheet is punched, the deformation amplitude is significantly reduced, and the silicon steel sheet is kept at a high-temperature annealing state after punching, further eliminating the stress of the silicon steel sheet, thus effectively improving the product quality and processing stability. More importantly, by real-time calculating the stress of the silicon steel sheet with the change of temperature, the stress of the silicon steel sheet can be more accurately controlled to be at the theoretical lowest point. Compared with traditional hot processing punching, it is more precise and can minimize the stress impact generated by punching the silicon steel sheet. Finally, since multiple layers of silicon steel sheets can be stored in the stress relief heater at one time and the drill directly punches in the stress relief heater, the drill can complete the punching operation of a batch of silicon steel sheets, further improving the work efficiency.

[0012] As a further technical measure, the interval stacking of the silicon steel sheets includes:

[0013] a. Obtain the current number of times the robotic arm grabs the silicon steel sheet, and calculate the current number of layers of silicon steel sheets in the stress relief heater according to the current number of times the robotic arm grabs the silicon steel sheet;

[0014] b. Calculate the descending time of the robotic arm when stacking the silicon steel sheets according to the current number of layers of silicon steel sheets in the stress relief heater;

[0015] c. Control the robotic arm to grab the silicon steel sheet on the silicon steel sheet placement rack, rise and translate it to the stacking position;

[0016] d. After the robotic arm descends to the calculated descending time at the stacking position, control the robotic arm to release the silicon steel sheet and then rise to the stacking position;

[0017] e. After the silicon steel sheet is placed at the target position, control the partition in the stress relief heater to translate above the silicon steel sheet;

[0018] f. Loop through steps a to e until the number of layers inside the stress relief heater is stacked to the maximum number of layers.

[0019] In the above technical solution, by obtaining the current number of times the robotic arm grabs the silicon steel sheet and calculating the current number of layers of silicon steel sheets in the stress relief heater, precise control of the stacking layers is achieved; according to the number of layers of silicon steel sheets, the descending and ascending times of the robotic arm are calculated, optimizing the movement trajectory of the robotic arm and improving the operation efficiency and accuracy; after the silicon steel sheet is placed at the target position, the isolation plate is driven to move above the silicon steel sheet for isolation, which can not only ensure uniform heating of each silicon steel sheet, but also prevent the mutual influence between silicon steel sheets, ensuring the heating and punching effects.

[0020] As a further technical measure, the current number of times the robotic arm grabs the silicon steel sheet starts from 0, and each time it grabs, the current number of times the robotic arm grabs the silicon steel sheet is incremented by 1. The calculation formula for the stacking layers of silicon steel sheets inside the stress relief heater is: V = V1 - N, where V represents the current number of layers of silicon steel sheets in the stress relief heater, V1 represents the current number of grabs by the silicon steel sheet grabber, and N is the number of grabbing failures. The grabbing failures include: the robotic arm fails to successfully grab the silicon steel sheet or the position of the grabbed silicon steel sheet deviates from the predetermined position by more than the set threshold. The position of the silicon steel sheet is detected in real time by an infrared sensor and the value of N is corrected.

[0021] In the above technical solution, the current number of layers of silicon steel sheets in the stress relief heater is accurately calculated by the formula V = V1 - N, avoiding operation errors caused by incorrect layer calculation. By detecting the position of the silicon steel sheet in real time with an infrared sensor and correcting the value of N, the situation of grabbing failure can be detected and corrected in time, ensuring the smooth progress of the stacking process.

[0022] As a further technical measure, the descending time is set with an initial time. Each time the current number of times V that the robotic arm grabs the silicon steel sheet is incremented by 1, the descending time is synchronously reduced by the time required for layer change on the basis of the initial time.

[0023] As a further technical measure, the reduction amplitude of the descending time and the ascending time does not exceed 50% of the initial time, and the single reduction amount is determined by the maximum acceleration threshold of the robotic arm. The specific calculation formula is:

[0024] T_new = T_initial - (T_initial * a * V),

[0025] where T_new is the new descending time, T_initial is the initial time, a is the maximum acceleration threshold of the robotic arm, and V is the current number of times the robotic arm grabs the silicon steel sheet.

[0026] In the above two technical solutions, as the number of times the robotic arm grasps the silicon steel sheet increases, the descent time and the ascent time synchronously reduce the time required for layer change based on the initial time, improving the operation efficiency; by restricting the reduction amplitude of the descent time and the ascent time to not exceed 50% of the initial time, and the single reduction amount is determined by the maximum acceleration threshold of the robotic arm, the safety and stability of the operation are ensured.

[0027] As a further technical means, calculating the thermal stress coefficient of the silicon steel sheet includes:

[0028] Calculating the thermal expansion coefficient of the silicon steel sheet according to the obtained initial length and the length change of the silicon steel sheet in each heating step;

[0029] Calculating the thermal stress coefficient of the silicon steel sheet according to the calculated thermal expansion coefficient, the known elastic modulus and Poisson's ratio of the silicon steel sheet.

[0030] As a further technical means, the calculation formula for the thermal expansion coefficient is:

[0031]

[0032] Wherein, α is the thermal expansion coefficient, L is the initial length of the silicon steel sheet, and dL is the length change amount caused by the temperature change dT.

[0033] As a further technical means, the calculation formula for the thermal stress coefficient is:

[0034]

[0035] Wherein, σ is the thermal stress coefficient, E is the elastic modulus of the material, α is the thermal expansion coefficient, v is Poisson's ratio, ΔT is the temperature difference between adjacent heating steps, k is the thermal conductivity correction factor, and t is the heating step duration.

[0036] In the above technical solutions, the thermal expansion coefficient and the thermal stress coefficient of the silicon steel sheet are accurately calculated by the formula, providing reliable data support for the subsequent punching operation. The accurate calculation of the thermal stress coefficient can ensure the accuracy and effectiveness of the punching operation, thereby improving the quality and stability of the product.

[0037] On the one hand, the present invention provides a stress relief heater for cooperating with the above method, including a position observation - calibration module, an isolation module, a heating module, a monitoring module, a calculation module, and a control module;

[0038] The position observation - calibration module is used to observe the position of the silicon steel sheet and perform position calibration to make the punching position of the silicon steel sheet match the isolation module.

[0039] The heating module is used to gradually increase and decrease the temperature of the silicon steel sheet according to the heating steps;

[0040] The isolation module is used to drive the isolation plate to move above the silicon steel sheet to isolate the silicon steel sheet after detecting that the silicon steel sheet is placed at the target position;

[0041] The monitoring module is used to monitor the internal temperature of the silicon heater, the initial length of the silicon steel sheet, and the length change of the silicon steel sheet at each heating step in real time;

[0042] The calculation module is used to calculate the thermal stress coefficient of the silicon steel sheet according to the initial length of the silicon steel sheet monitored by the monitoring module and the length change of the silicon steel sheet at each heating step,

[0043] The control module is used to uniformly call the heating module, isolation module, monitoring module, and calculation module, and control the punching operation and annealing treatment according to the calculation results. The specific control process is as follows: First, the control module receives the thermal stress coefficient calculated by the calculation module. When the coefficient reaches the preset target value, the control module activates the punching drill to perform the punching operation; Subsequently, the control module adjusts the heater to the annealing temperature and continues for the stress relief time period; Finally, the control module instructs the robotic arm to remove the silicon steel sheet.

[0044] In the above technical solution, the heater adopts a modular design, including a position observation - calibration module, isolation module, heating module, monitoring module, calculation module, and control module, etc. These modules work together to achieve precise control of the entire stress relief process; Through automated and intelligent control methods, the production efficiency is improved and the labor cost is reduced; The precise monitoring and calculation modules can ensure the accuracy and effectiveness of the heating and punching operations, thus ensuring the quality and stability of the product. At the same time, the modular design also facilitates maintenance and upgrading, improving the reliability and service life of the equipment.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The automation and programming of the entire stress relief process are realized, improving production efficiency and operation accuracy; 2. The robotic arm is controlled to place silicon steel sheets into the stress relief heater in an interval stacking manner, and the heating temperature is gradually increased step by step according to the heating steps, ensuring uniform heating of the silicon steel sheets, reducing the generation of thermal stress. By real-time monitoring the length change of the silicon steel sheets and combining the temperature gradient data, the thermal stress coefficient of the silicon steel sheets is calculated, providing accurate data support for subsequent drilling operations; 3. By heating the silicon steel sheets, the silicon steel sheets are softened, significantly reducing the stress of the silicon steel sheets themselves. Then, a drill bit is used to drill the silicon steel sheets at this time. When the softened silicon steel sheets are drilled, the deformation amplitude is significantly reduced, and the silicon steel sheets are kept in a high-temperature annealing state after drilling, further eliminating the stress of the silicon steel sheets, thereby effectively improving the quality of the product and the stability of processing; 4. More importantly, by real-time calculating the stress of the silicon steel sheets with the change of temperature, the stress of the silicon steel sheets can be more accurately controlled to be at the theoretically lowest point. Compared with traditional hot processing drilling, it is more precise and can minimize the stress impact generated by drilling the silicon steel sheets; 5. Finally, since multiple layers of silicon steel sheets can be stored in the stress relief heater at one time, and the drill bit directly drills in the stress relief heater, the drill bit can complete the drilling operation of batch silicon steel sheets, further improving the work efficiency; 6. By obtaining the current number of times the robotic arm grabs the silicon steel sheets, the current number of layers of silicon steel sheets in the stress relief heater is calculated, realizing precise control of the stacking layers; according to the number of layers of silicon steel sheets, the descending and ascending times of the robotic arm are calculated, optimizing the movement trajectory of the robotic arm, improving operation efficiency and accuracy; after the silicon steel sheets are placed at the target position, the isolation plate is driven to move above the silicon steel sheets for isolation, which can not only ensure uniform heating of each silicon steel sheet, but also prevent the mutual influence between the silicon steel sheets, ensuring the heating and drilling effects; 7. As the number of times the robotic arm grabs the silicon steel sheets increases, the descending time and the ascending time are synchronously reduced on the basis of the initial time to reduce the layer change time, improving operation efficiency; by limiting the reduction amplitude of the descending time and the ascending time not to exceed 50% of the initial time, and the single reduction amount is determined by the maximum acceleration threshold of the robotic arm, the safety and stability of the operation are ensured; 8. The heater adopts a modular design, including a position observation - calibration module, an isolation module, a heating module, a monitoring module, a calculation module, a control module, etc. The modules work together to achieve precise control of the entire stress relief process; through an automated and intelligent control method, production efficiency is improved and labor costs are reduced; the precise monitoring and calculation modules can ensure the accuracy and effectiveness of the heating and drilling operations, thereby ensuring the quality and stability of the product. At the same time, the modular design is also convenient for maintenance and upgrading, improving the reliability and service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The flowchart of a method for eliminating punching stress of transformer silicon steel sheets provided by an embodiment of the present invention;

[0047] Figure 2 The schematic diagram of the working principle of the PLC controller, robotic arm and stress elimination heater provided by an embodiment of the present invention. Specific embodiments

[0048] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0049] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0050] As Figure 1 shown, on the one hand, the present invention provides a method for eliminating punching stress of transformer silicon steel sheets, including:

[0051] Program initialization;

[0052] Control the robotic arm to grab the silicon steel sheets and place the grabbed silicon steel sheets into the stress elimination heater in an interval stacking manner. Control the stress elimination heater to gradually increase the heating temperature step by step according to the heating steps, and continue for the target time at each heating step;

[0053] Obtain the initial length of the silicon steel sheet and the length change amount of the silicon steel sheet in each heating step, and calculate the thermal stress coefficient of the silicon steel sheet in combination with the temperature gradient data;

[0054] When the thermal stress coefficient of the silicon steel sheet reaches the target value, control the punching drill to extend from the outside of the stress elimination heater into the inside of the stress elimination heater from top to bottom, and punch the stacked silicon steel sheets one by one;

[0055] Control the punching drill to lift until it disengages from the stress elimination heater, control the stress elimination heater to lower the temperature to the annealing temperature, and continue for the stress elimination time period, and then control the robotic arm to take out the silicon steel sheets.

[0056] In the above technical solution, the automation and programming of the entire stress relief process are realized, improving production efficiency and operation accuracy. The robotic arm is controlled to place silicon steel sheets into the stress relief heater in an interval stacking manner, and the heating temperature is gradually increased step by step according to the heating steps to ensure uniform heating of the silicon steel sheets, reducing the generation of thermal stress. By real-time monitoring the length change of the silicon steel sheets and combining the temperature gradient data, the thermal stress coefficient of the silicon steel sheets is calculated, providing accurate data support for subsequent punching operations. By heating the silicon steel sheets, the silicon steel sheets are softened, greatly reducing the stress of the silicon steel sheets themselves. Then, a drill bit is used to punch the silicon steel sheets at this time. When the softened silicon steel sheets are punched, the deformation amplitude is greatly reduced, and after punching, the silicon steel sheets are kept in a high-temperature annealing state, further eliminating the stress of the silicon steel sheets, thus effectively improving the product quality and processing stability. More importantly, by real-time calculating the stress of the silicon steel sheets with the change of temperature, the stress of the silicon steel sheets can be more accurately controlled to be at the theoretical lowest point. Compared with traditional hot processing punching, it is more precise and can minimize the stress impact generated by punching the silicon steel sheets. Finally, since multiple layers of silicon steel sheets can be stored in the stress relief heater at one time and the drill bit directly punches in the stress relief heater, the drill bit can complete the punching operation of batch silicon steel sheets, further improving the work efficiency.

[0057] In this embodiment, the heating step is set at 40 degrees Celsius, and there are at least 10 heating steps in total. However, it should be noted that the precondition for the heating step is that the temperature in the stress relief heater reaches 400 degrees Celsius. Before reaching 400 degrees Celsius, it is not counted as a heating step.

[0058] In addition, the target time within each heating step in the stress relief heater is set at 15 - 30 minutes, and the specific time is determined according to the thickness of the silicon steel sheets. For every 0.1 mm increase in the thickness of the silicon steel sheets, the target time is delayed by 5 minutes.

[0059] In this embodiment, the interval stacking of the silicon steel sheets includes:

[0060] a. Obtain the current number of times the robotic arm grabs the silicon steel sheets, and calculate the current number of layers of silicon steel sheets in the stress relief heater according to the current number of times the robotic arm grabs the silicon steel sheets;

[0061] b. Calculate the descending time of the robotic arm when stacking the silicon steel sheets according to the current number of layers of silicon steel sheets in the stress relief heater;

[0062] c. Control the robotic arm to grab the silicon steel sheets on the silicon steel sheet placement rack, rise and translate to the stacking position;

[0063] d. After the robotic arm descends to the calculated descending time at the stacking position, control the robotic arm to release the silicon steel sheets and then rise to the stacking position;

[0064] e. After the silicon steel sheet is obtained and placed at the target position, control the inner partition of the stress relief heater to translate above the silicon steel sheet;

[0065] f. Repeat steps a to e until the number of layers inside the stress relief heater is stacked to the maximum number of layers.

[0066] In the above technical solution, by obtaining the current number of times the robotic arm grabs the silicon steel sheet and calculating the current number of silicon steel sheets in the stress relief heater, precise control of the stacking number of layers is achieved; based on the number of silicon steel sheets, the descending and ascending times of the robotic arm are calculated, optimizing the movement trajectory of the robotic arm, improving the operation efficiency and accuracy; after the silicon steel sheet is placed at the target position, the isolation plate is driven to move above the silicon steel sheet for isolation, preventing the mutual influence between the silicon steel sheets and ensuring the heating and punching effects.

[0067] In this embodiment, the current number of times the robotic arm grabs the silicon steel sheet starts from 0, and each time it grabs, the current number of times the robotic arm grabs the silicon steel sheet is incremented by 1. The calculation formula for the stacked number of silicon steel sheets inside the stress relief heater is: V = V1 - N, where V represents the current number of silicon steel sheets in the stress relief heater, V1 represents the current number of grabs of the silicon steel sheet grab, and N is the number of grab failures. Grab failures include: the robotic arm fails to successfully grab the silicon steel sheet or the position of the grabbed silicon steel sheet deviates from the predetermined position by more than the set threshold. The position of the silicon steel sheet is detected in real time by an infrared sensor and the value of N is corrected.

[0068] In the above technical solution, the current number of silicon steel sheets in the stress relief heater is accurately calculated by the formula V = V1 - N, avoiding operation errors caused by incorrect layer number calculation. By detecting the position of the silicon steel sheet in real time by an infrared sensor and correcting the value of N, the situation of grab failure can be detected and corrected in time, ensuring the smooth progress of the stacking process.

[0069] In this embodiment, the descending time is set with an initial time. Each time the current number of times V that the robotic arm grabs the silicon steel sheet is incremented by 1, the descending time is synchronously reduced by the time required for layer change based on the initial time.

[0070] In this embodiment, the reduction amplitude of the descending time and the ascending time does not exceed 50% of the initial time, and the single reduction amount is determined by the maximum acceleration threshold of the robotic arm. The specific calculation formula is:

[0071] T_new = T_initial - (T_initial * a * V),

[0072] where T_new is the new descending time, T_initial is the initial time, a is the maximum acceleration threshold of the robotic arm, and V is the current number of times the robotic arm grabs the silicon steel sheet.

[0073] In the above two technical solutions, as the number of times the robotic arm grabs silicon steel sheets increases, the descent time and the ascent time synchronously reduce the time required for layer change based on the initial time, improving the operation efficiency; by limiting the reduction amplitude of the descent time and the ascent time to not exceed 50% of the initial time, and the single reduction amount is determined by the maximum acceleration threshold of the robotic arm, the safety and stability of the operation are ensured.

[0074] In this embodiment, calculating the thermal stress coefficient of the silicon steel sheet includes:

[0075] According to the obtained initial length and the length change of the silicon steel sheet in each heating step, calculate the thermal expansion coefficient of the silicon steel sheet;

[0076] According to the calculated thermal expansion coefficient and the known elastic modulus and Poisson's ratio of the silicon steel sheet, calculate the thermal stress coefficient of the silicon steel sheet.

[0077] In this embodiment, the calculation formula for the thermal expansion coefficient is:

[0078]

[0079] Wherein, α is the thermal expansion coefficient, L is the initial length of the silicon steel sheet, and dL is the length change amount caused by the temperature change dT.

[0080] In this embodiment, the calculation formula for the thermal stress coefficient is:

[0081]

[0082] Wherein, σ is the thermal stress coefficient, E is the elastic modulus of the material, α is the thermal expansion coefficient, v is Poisson's ratio, ΔT is the temperature difference between adjacent heating steps, k is the heat conduction correction factor, and t is the heating step duration, specifically as shown in the following table:

[0083] High-temperature stress coefficient table of silicon steel sheet

[0084] Temperature (°C) Coefficient of thermal expansion (α, 10-6 / °C) Elastic modulus (E, GPa) Stress coefficient (α·E, MPa / °C) 400 12.0 160 1.92 450 12.5 150 1.88 500 13.0 140 1.82 550 13.5 130 1.76 600 14.0 120 1.68 650 14.5 110 1.60 700 15.0 100 1.50 750 15.5 90 1.40 800 16.0 80 1.28 850 16.5 70 1.16 900 17.0 60 1.02

[0085] In the above technical solution, the thermal expansion coefficient and the thermal stress coefficient of the silicon steel sheet are accurately calculated by the formula, providing reliable data support for the subsequent punching operation. The accurate calculation of the thermal stress coefficient can ensure the accuracy and effectiveness of the punching operation, thereby improving the quality and stability of the product.

[0086] Such as Figure 2 shown, based on the same technical concept of the above embodiment, on the one hand, the present invention provides a stress relief heater, including a position observation - calibration module, an isolation module, a heating module, a monitoring module, a calculation module, and a control module;

[0087] A position observation - calibration module, used to observe the position of the silicon steel sheet and perform position calibration to make the punching position of the silicon steel sheet match the isolation module.

[0088] A heating module, used to gradually increase and decrease the temperature of the silicon steel sheet according to heating steps.

[0089] An isolation module, used to drive the isolation plate to move above the silicon steel sheet to isolate the silicon steel sheet after detecting that the silicon steel sheet is placed at the target position.

[0090] A monitoring module, used to monitor the internal temperature of the silicon heater, the initial length of the silicon steel sheet, and the length change of the silicon steel sheet at each heating step in real time.

[0091] A calculation module, used to calculate the thermal stress coefficient of the silicon steel sheet based on the initial length of the silicon steel sheet detected by the monitoring module and the length change of the silicon steel sheet at each heating step.

[0092] A control module, used to uniformly call the heating module, isolation module, monitoring module, and calculation module, and control the punching operation and annealing process according to the calculation results. The specific control process is as follows: First, the control module receives the thermal stress coefficient calculated by the calculation module. When the coefficient reaches the preset target value, the control module activates the punching drill to perform the punching operation. Subsequently, the control module adjusts the heater to the annealing temperature and maintains it for the stress relief time period. Finally, the control module instructs the robotic arm to take out the silicon steel sheet.

[0093] In this embodiment, the stress relief heater can store up to 30 layers of silicon steel sheets at most. The distance between each layer of silicon steel sheets is maintained at 5 - 8 cm. The partition plate is provided with reserved through holes for the drill bit to pass through during punching.

[0094] In the above technical solution, the heater adopts a modular design, including a position observation - calibration module, an isolation module, a heating module, a monitoring module, a calculation module, and a control module. Each module works in coordination to achieve precise control of the entire stress relief process; through automated and intelligent control methods, the production efficiency is improved and the labor cost is reduced; the precise monitoring and calculation modules can ensure the accuracy and effectiveness of the heating and punching operations, thus ensuring the quality and stability of the product. At the same time, the modular design is also convenient for maintenance and upgrade, improving the reliability and service life of the equipment.

[0095] In this embodiment, the entire punching system includes a PCL controller, a robotic arm, and a stress relief heater. After the operator initializes the program of the PCL controller, the robotic arm is controlled to repeatedly stack silicon steel sheets into the stress relief heater, and then the stress relief heater is used to heat the silicon steel sheets to relieve stress, and then the silicon steel sheets in the stress relief heater are directly punched at high temperature.

[0096] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for eliminating punching stress of transformer silicon steel sheets, characterized in that Including: Program initialization; Controlling the robotic arm to grasp silicon steel sheets and placing the grasped silicon steel sheets into the stress relief heater in a stacked manner at intervals, controlling the stress relief heater to gradually increase the heating temperature step by step according to the heating steps, and maintaining at each heating step until the target time; Obtaining the initial length of the silicon steel sheet and the length change of the silicon steel sheet at each heating step, and calculating the thermal stress coefficient of the silicon steel sheet in combination with the temperature gradient data; When the thermal stress coefficient of the silicon steel sheet reaches the target value, controlling the punching drill to extend from the outside of the stress relief heater into the inside of the stress relief heater from top to bottom, and punching the stacked silicon steel sheets one by one; Controlling the punching drill to lift until it disengages from the stress relief heater, controlling the stress relief heater to lower the temperature to the annealing temperature, and maintaining it until the stress relief time period, and then controlling the robotic arm to take out the silicon steel sheet.

2. A method for eliminating punching stress of transformer silicon steel sheets according to claim 1, characterized in that: The stacked placement of the silicon steel sheets includes: a. Obtaining the current number of times the robotic arm grasps the silicon steel sheet, and calculating the current number of layers of silicon steel sheets in the stress relief heater according to the current number of times the robotic arm grasps the silicon steel sheet; b. Calculating the descending time of the robotic arm when stacking the silicon steel sheets according to the current number of layers of silicon steel sheets in the stress relief heater; c. Controlling the robotic arm to grasp the silicon steel sheet on the silicon steel sheet placement rack, rise and translate to the stacking position; d. Controlling the robotic arm to descend at the stacking position until the calculated descending time is reached, and after the robotic arm releases the silicon steel sheet, rising to the stacking position; e. After obtaining that the silicon steel sheet is placed at the target position, controlling the partition plate in the stress relief heater to translate above the silicon steel sheet; f. Repeatedly executing steps a to e until the number of layers inside the stress relief heater is stacked to the maximum number of layers.

3. A method for eliminating punching stress of transformer silicon steel sheets according to claim 2, characterized in that: The current number of times the robotic arm grasps the silicon steel sheet starts from 0, and each time it grasps, the current number of times the robotic arm grasps the silicon steel sheet is incremented by 1. The calculation formula for the stacked number of silicon steel sheets inside the stress relief heater is: V = V1 - N, where V represents the current number of layers of silicon steel sheets in the stress relief heater, V1 represents the current number of times the silicon steel sheet grabber grasps, and N is the number of grasping failures. The grasping failure includes: the robotic arm fails to successfully grasp the silicon steel sheet or the position of the grasped silicon steel sheet deviates from the predetermined position by more than the set threshold. The position of the silicon steel sheet is detected in real time by an infrared sensor and the N value is corrected.

4. A method for eliminating punching stress of transformer silicon steel sheets according to any one of claims 2-3, characterized in that: The descending time is set with an initial time. Each time the current number of times V that the robotic arm grasps the silicon steel sheet is incremented by 1, the descending time is synchronously reduced by the time required for layer change on the basis of the initial time.

5. A method for eliminating punching stress of transformer silicon steel sheets according to any one of claims 4, characterized in that: The reduction amplitude of the descending time and the ascending time does not exceed 50% of the initial time, and the single reduction amount is determined by the maximum acceleration threshold of the robotic arm. The specific calculation formula is: T_new = T_initial - (T_initial * a * V), where T_new is the new descending time, T_initial is the initial time, a is the maximum acceleration threshold of the robotic arm, and V is the current number of times the robotic arm grasps the silicon steel sheet.

6. A method for eliminating punching stress of transformer silicon steel sheets according to claim 1, characterized in that: Calculating the thermal stress coefficient of the silicon steel sheet includes: Calculating the thermal expansion coefficient of the silicon steel sheet according to the obtained initial length and the length change of the silicon steel sheet at each heating step; Calculate the thermal stress coefficient of the silicon steel sheet based on the calculated coefficient of thermal expansion and the known elastic modulus and Poisson's ratio of the silicon steel sheet.

7. A method for eliminating punching stress of transformer silicon steel sheets according to claim 6, characterized in that: The formula for the coefficient of thermal expansion is: where α is the coefficient of thermal expansion, L is the initial length of the silicon steel sheet, and dL is the change in length caused by a temperature change dT.

8. A method for eliminating punching stress of transformer silicon steel sheets according to claim 7, characterized in that: The formula for the thermal stress coefficient is: where σ is the thermal stress coefficient, E is the elastic modulus of the material, α is the coefficient of thermal expansion, v is Poisson's ratio, ΔT is the temperature difference between adjacent heating steps, k is the thermal conductivity correction factor, and t is the duration of the heating step.

9. A stress relief heater, characterized in that: It includes a position observation - calibration module, an isolation module, a heating module, a monitoring module, a calculation module, and a control module; The position observation - calibration module is used to observe the position of the silicon steel sheet and perform position calibration to make the punching position of the silicon steel sheet match the isolation module. The heating module is used to gradually increase and decrease the temperature of the silicon steel sheet according to the heating steps. The isolation module is used to drive the isolation plate to move above the silicon steel sheet to isolate the silicon steel sheet after detecting that the silicon steel sheet is placed at the target position. The monitoring module is used to continuously monitor the internal temperature of the silicon heater, the initial length of the silicon steel sheet, and the change in length of the silicon steel sheet in each heating step. The calculation module is used to calculate the thermal stress coefficient of the silicon steel sheet based on the initial length of the silicon steel sheet and the change in length of the silicon steel sheet in each heating step monitored by the monitoring module. The control module is used to uniformly call the heating module, isolation module, monitoring module, and calculation module, and control the punching operation and annealing treatment according to the calculation results. The specific control process is as follows: First, the control module receives the thermal stress coefficient calculated by the calculation module. When this coefficient reaches the preset target value, the control module activates the punching drill to perform the punching operation. Subsequently, the control module adjusts the heater to the annealing temperature and maintains it for the stress relief time period. Finally, the control module instructs the robotic arm to remove the silicon steel sheet.

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