Automatic calibration method for accurate discharge control of spray gun

Abstract

The invention discloses an automatic calibration method for accurate discharge control of a spray gun. The automatic calibration method comprises the following steps: S1, recording an initial position; s2, recording the maximum travel; s3, the discharging position is recorded; s4, the stopping position is recorded; s5, calibrating ejector pin shooting response time; the actual shooting response time Topen is calculated; s6, calibrating thimble gun closing response time; actual gun closing response time Tclose is calculated; s7, the compensation time is calculated based on the spraying speed according to the actual deviation, accurate discharging control is achieved by calibrating the discharging time and the stopping time through the method, the calibration process is simple, consumed time is short, it can be guaranteed that the time error is within + / -50 ms, the actual spraying precision error is within 20 mm, the high-precision spraying process requirement is met, and the method is suitable for large-scale popularization and application. And meanwhile, comprehensive compensation can be carried out on different pressures, materials, nozzles and material characteristic changes, the consistent spraying effect is ensured, the control stability of the spray gun during long-term use is kept, the phenomena of over-spraying and missing spraying are effectively reduced, and the calibration workload is low.

Description

Technical Field

[0001] The invention relates to the technical field of automated spraying, and in particular to an automatic calibration method for precise control of spray gun discharge. Background Art

[0002] In the field of industrial automated spraying, precise control of the spray gun discharge is crucial when robots are performing tasks such as spraying putty, paint, and other materials. Traditional spray guns usually use a pin structure to control the switch, but due to differences in pin length, elasticity, pressure, and nozzle type, the discharge time of the spray gun often deviates, resulting in overspray or missed spray during the spraying process, which in turn affects product quality.

[0003] Therefore, it is urgent to design an automatic calibration method for precise control of spray gun discharge to overcome one or more of the above-mentioned deficiencies of the prior art. Summary of the invention

[0004] The technical solution adopted by the present invention to solve the above technical problems is: an automatic calibration method for precise control of spray gun discharge, characterized in that it includes the following steps:

[0005] S1, record the initial position; start calibration, execute the gun closing operation, and record the limit position of the spray gun ejector pin moving to the complete gun closing as L0;

[0006] S2, record the maximum stroke; control the ejector to move, record the moment when the ejector starts to move as T1, and record the position of the ejector when it moves to the maximum stroke as L1, and then reset to position L0;

[0007] S3, record the discharge position; execute the gun firing operation, control the ejector pin of the spray gun to move toward position L1, until the material is discharged from the end of the spray gun, and record the discharge position as L2; ​​and continue to control the ejector pin to move to position L1;

[0008] S4, record the stop position, execute the gun closing operation, control the ejector to move from position L1 to position L0, until the end of the spray gun stops discharging, and record the current actual stop position as L3;

[0009] S5, calibrate the ejector firing response time; control the ejector to move again and record the current time T1, when the ejector passes L2, record the time as T2, and calculate the actual firing response time Topen;

[0010] S6, calibrate the ejector gun closing response time; execute the gun closing operation, record the gun closing time as T3, when the ejector passes through position L3, record the current time as T4, and calculate the actual gun closing response time Tclose;

[0011] S7. Calculate compensation time based on the spraying speed according to the actual deviation.

[0012] In a preferred embodiment, in step S5, the firing response time Topen=T2-T1.

[0013] In a preferred embodiment, in step S6, the gun closing response time Tclose=T4-T3.

[0014] In a preferred embodiment, the calculation of the compensation time in step S7 comprises the following steps:

[0015] S71, measuring the blank area Δx_open between the shooting position and the actual paint application position on the wall;

[0016] S72, measuring the extended area Δx_close between the gun closing position and the actual paint application position on the wall;

[0017] S73. The calculation formula for the firing delay time is as follows:

[0018] ΔTopen=Δx_open / V

[0019] S74, calculation of the gun closing delay time, the formula is as follows:

[0020] ΔTclose=Δx_close / V

[0021] S75. Calculation of the switch gun correction time, the formula is as follows:

[0022] Topen_real=Topen+ΔTopen

[0023] Tclose_real=Tclose+ΔTclose

[0024] Among them, V is the speed control closed loop provided by the servo monitoring module; Topen_real is the correction time for shooting, Topen is the actual response time for shooting, and ΔTopen is the delay time for shooting.

[0025] In a preferred embodiment, each position is recorded using one or more of a proximity switch sensor and a servo encoder.

[0026] The beneficial effects of the present invention are as follows: accurate discharge control is achieved by calibrating the discharge time and the stop time; the calibration process is simple and time-saving, and can ensure that the time error is within ±50ms, and the actual spraying accuracy error is within 20mm, meeting the requirements of high-precision spraying process; at the same time, comprehensive compensation for changes in different pressures, materials, nozzles and material properties can be achieved to ensure consistent spraying effects, maintain the stability of spray gun control during long-term use, effectively reduce overspray and leaking spray, and the calibration workload is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0029] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms, "connection" and "installation" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. In addition, "connection" can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed" means that they are connected to each other and the relative position relationship after connection remains unchanged. The directional terms mentioned in the embodiments of the present invention, such as "inside", "outside", "top", "bottom", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present invention, 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 on the embodiments of the present invention.

[0030] In the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0031] In the embodiments of the present invention, "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0032] References to "one embodiment" or "some embodiments" etc. described in this specification mean that one or more embodiments of the present invention include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0033] like Figure 1 As shown, the present invention provides an automatic calibration method for precise control of spray gun discharge, which is characterized by comprising the following steps:

[0034] S1, record the initial position; start calibration, execute the gun closing operation, and record the limit position of the spray gun ejector pin moving to the complete gun closing as L0;

[0035] S2. Record the maximum stroke; control the movement of the ejector, record the moment when the ejector starts to move as T1, and record the position of the ejector when it moves to the maximum stroke as L1, and then reset it to position L0; when the ejector stroke is insufficient or exceeds the rated range, set a limit on the maximum ejector stroke, stop the operation when the stroke exceeds the limit, and reset it through stroke verification. If the ejector cannot be reset to L0, use a closed-loop control system to adjust the ejector position through feedback to ensure that it can return to L0.

[0036] S3, record the discharge position; execute the gun operation, control the ejector pin of the spray gun to move toward position L1, until the material is discharged from the end of the spray gun, and record the discharge position as L2; ​​and continue to control the ejector pin to move to position L1; to ensure the accuracy of the detection, when recording the discharge, use a slow movement method to record, that is, slowly compress the ejector pin through the pumping system to move until the material is discharged from the end of the spray gun. When the discharge detection is insensitive or misjudged, the motor can be controlled to move at a certain step length, such as moving the encoder value of 5000, until the material is discharged. The fan-shaped spray material is sprayed out, which is the actual gun position. Generally, the encoding value differs by about 100 when the material is discharged and when it is not discharged, and the error is about 10ms. The position can be confirmed by multiple detections, such as adding 100 to have material sprayed out, and subtracting 100 to have no material sprayed out, and the position can be confirmed repeatedly several times.

[0037] S4, record the stop position, execute the gun closing operation, control the ejector pin to move from position L1 to position L0, until the end of the spray gun stops discharging material, and record the current actual stop position as L3; the stop record also adopts the method of slowly compressing the ejector pin to ensure the accuracy of the position.

[0038] S5, calibrate the ejector firing response time; control the ejector to move again and record the current time T1, when the ejector passes L2, record the time as T2, and calculate the actual firing response time Topen;

[0039] S6, calibrate the ejector gun closing response time; execute the gun closing operation, record the gun closing time as T3, when the ejector passes through position L3, record the current time as T4, and calculate the actual gun closing response time Tclose;

[0040] S7. Calculate compensation time based on the spraying speed according to the actual deviation.

[0041] Furthermore, in step S5, the shooting response time Topen=T2-T1.

[0042] Furthermore, in step S6, the gun closing response time Tclose=T4-T3.

[0043] Furthermore, the calculation of the compensation time in step S7 includes the following steps:

[0044] S71, measuring the blank area Δx_open between the shooting position and the actual paint application position on the wall;

[0045] S72, measuring the extended area Δx_close between the gun closing position and the actual paint application position on the wall;

[0046] S73. The calculation formula for the firing delay time is as follows:

[0047] ΔTopen=Δx_open / V

[0048] S74, calculation of the gun closing delay time, the formula is as follows:

[0049] ΔTclose=Δx_close / V

[0050] S75. Calculation of the switch gun correction time, the formula is as follows:

[0051] Topen_real=Topen+ΔTopen

[0052] Tclose_real=Tclose+ΔTclose

[0053] Among them, V is the speed control closed loop provided by the servo monitoring module; Topen_real is the correction time for shooting, Topen is the actual response time for shooting, and ΔTopen is the delay time for shooting.

[0054] Furthermore, each position is recorded using one or more of a proximity switch sensor and a servo encoder.

[0055] Specifically, the response time of the switch gun refers to the time from the control command to the servo driver receiving the signal, the response time of the servo driver, and the time until the servo motor completes moving to the target. Before setting, first record the initial position and maximum stroke position of the ejector, then record the discharge position and the stop position, and then determine the actual discharge time and stop time of the spray gun on this basis, after calculating the actual discharge time and the actual stop time of the spray gun; in order to ensure the accuracy of the position, the switch sensor and the servo encoder are used in this embodiment to double record to ensure the accuracy of the position; according to the deviation between the actual spray position and the theoretical position, the compensation time is calculated based on the spray speed, and the spray gun switch time is updated, so that the final spray error is within the control target range. In this way, the calibration process is simple, time-consuming, and can ensure that the time error is within ±50ms, and the actual spray accuracy error is within 20mm, meeting the requirements of high-precision spraying process. In this way, it is possible to achieve comprehensive compensation for different pressures, materials, nozzles and material property changes, ensure consistent spraying effects, maintain the stability of spray gun control during long-term use, effectively reduce overspray and leak spray, and the calibration workload is low.

[0056] Among them, there will be a delay when the spray gun is turned on or off. The delay in opening the gun will cause the paint fired by the spray gun to take a certain amount of time to reach the wall. The delay in closing the gun will cause the remaining paint to continue to be sprayed after the spray gun is turned off, causing the paint to exceed the expected area and affect the spraying effect. Therefore, it is necessary to compensate for the opening and closing time of the gun to reduce the impact on the spraying effect. The calculation of compensation includes the following steps:

[0057] Analyze the existing errors, measure the length of the blank area Δx_open between the gun opening position and the actual paint application position, and measure the length of the extended area Δx_close between the gun closing position and the actual paint application position;

[0058] Calculate the compensation value, first calculate the gun opening delay time ΔTopen = Δx_open / V; then calculate the gun closing delay time ΔTclose = Δx_close / V; then calculate the actual gun opening correction time Topen_real = Topen + ΔTopen, and finally calculate the actual gun closing correction time Tclose_real = Tclose + ΔTclose;

[0059] Where V is the speed control closed loop provided by the servo monitoring module.

[0060] Through experimental tests, it is found that under the same pressure (20Mpa) and spray distance (500mm), the deviations Δx_open and Δx_close are basically consistent, within a range of 50ms, and fixed parameter configuration can be performed.

[0061] The final compensation value mainly depends on the fine-tuning based on the spray gun calibration values ​​Topen and Tclose, and finally the Topen_real and Tclose_real values ​​are used.

[0062] In summary, the control accuracy of the spray gun can be effectively improved, overspray and missed spray phenomena can be significantly reduced, and the calibration workload can be reduced, so that the spray gun can adapt to the automated spraying needs under various working conditions.

[0063] The present invention is not limited to what is described in the specification and implementation modes, and therefore additional advantages and modifications can be easily realized by those skilled in the art. Therefore, without departing from the spirit and scope of the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details, representative devices, and illustrative examples shown and described herein.

Claims

1. An automatic calibration method for precise control of spray gun discharge, characterized in that: The following steps are involved: S1, record the initial position; Start calibration, execute the gun closing operation, and record the limit position when the spray gun ejector moves to the complete gun closing position as L0; S2, record the maximum stroke; control the ejector to move, record the moment when the ejector starts to move as T1, and record the position of the ejector when it moves to the maximum stroke as L1, and then reset to position L0; S3, record the discharge position; execute the gun firing operation, control the ejector pin of the spray gun to move toward position L1, until the material is discharged from the end of the spray gun, and record the discharge position as L2; ​​and continue to control the ejector pin to move to position L1; S4, record the stop position, execute the gun closing operation, control the ejector to move from position L1 to position L0, until the end of the spray gun stops discharging, and record the current actual stop position as L3; S5, calibrate the ejector firing response time; control the ejector to move again and record the current time T1, when the ejector passes L2, record the time as T2, and calculate the actual firing response time Topen; S6, calibrate the ejector gun closing response time; execute the gun closing operation, record the gun closing time as T3, when the ejector passes through position L3, record the current time as T4, and calculate the actual gun closing response time Tclose; S7. Calculate compensation time based on the spraying speed according to the actual deviation.

2. The automatic calibration method for precise control of spray gun discharge according to claim 1, characterized in that: In step S5, the firing response time Topen=T2-T1.

3. The automatic calibration method for precise control of spray gun discharge according to claim 1, characterized in that: In step S6, the gun closing response time Tclose=T4-T3.

4. The automatic calibration method for precise control of spray gun discharge according to claim 1, characterized in that: The calculation of the compensation time in step S7 includes the following steps: S71, measuring the blank area Δx_open between the shooting position and the actual paint application position on the wall; S72, measuring the extended area Δx_close between the gun closing position and the actual paint application position on the wall; S73. The calculation formula for the firing delay time is as follows: ΔTopen=Δx_open / V S74, calculation of the gun closing delay time, the formula is as follows: ΔTclose=Δx_close / V S75. Calculation of the switch gun correction time, the formula is as follows: Topen_real=Topen+ΔTopen Tclose_real=Tclose+ΔTclose Among them, V is the speed control closed loop provided by the servo monitoring module; Topen_real is the correction time for shooting, Topen is the actual response time for shooting, and ΔTopen is the delay time for shooting.

5. The automatic calibration method for precise control of spray gun discharge according to claim 1, characterized in that: Each position is recorded using one or more of a proximity switch sensor and a servo encoder.

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