A machine vision-based dispensing and marking method

Abstract

A machine vision-based dispensing and marking method includes the following steps: a certain number of temperature-sensing packs are placed on a conveyor belt with the injection port facing upwards and move unidirectionally with the conveyor belt; after entering the image acquisition range of a first image acquisition unit, the conveyor belt stops, the first image acquisition unit acquires image information within the range and transmits it to a vision positioning system; the vision positioning system recognizes and calculates the images, establishes a parameter list, and stores the geometric center of the temperature-sensing pack and the position of the injection port at the dispensing and marking positions; the parameter list is used to control the dispensing and laser head. This invention integrates the dispensing and marking operations in one step, uses machine vision to identify the position of the temperature-sensing pack, and adapts the temperature-sensing pack to a specific stepped shape. The injection port is placed on the stepped ring surface, and the marking is engraved in an arc shape on the stepped ring surface, avoiding the injection port.

Description

Technical Field

[0001] This invention relates to the fields of dispensing and laser marking, and specifically to a dispensing and marking method based on machine vision. Background Technology

[0002] The temperature sensor is the core component inside the temperature controller. It is used to sense the temperature of the material it comes into contact with, usually the ambient temperature, and then generates a displacement output through the temperature sensing medium inside it.

[0003] Currently, the temperature sensing medium inside the temperature sensing bulb is generally paraffin wax. Copper powder can be added to it to improve the temperature sensing coefficient. The proportion of wax and copper powder in this composite temperature sensing medium directly affects the hysteresis of the installed components. Hysteresis is an important indicator in temperature control valves. Therefore, the preparation of this composite temperature sensing medium has strict requirements. At the same time, the process of loading this solid composite medium into the temperature sensing bulb is difficult.

[0004] Furthermore, the temperature sensing medium can also be liquid ethyl acetate. The expansion and hysteresis properties of ethyl acetate have been tested and found to meet the temperature control requirements of the temperature control head. Based on the fluid characteristics of liquid ethyl acetate, when preparing the temperature sensing bag, it is only necessary to press down the nozzle of the injection gun to open the seal of the injection port on the temperature sensing bag, and then directly inject it. In terms of processability, it has a preparation advantage over paraffin.

[0005] After ethyl acetate injection is completed, the seal is reset to maintain the airtightness of the temperature sensing bulb. During the temperature sensing process, the expansion of ethyl acetate creates pressure changes within the bulb, which in turn act on the displacement output component to generate displacement output. At this time, due to the pressure inside the bulb and the fluid properties of ethyl acetate, the sensing medium can easily leak out through the injection port. More importantly, ethyl acetate is volatile, creating a channel for outward evaporation at the injection port, resulting in loss of the medium within the bulb. Consequently, the output accuracy of the temperature sensing bulb used for feedback control is not guaranteed. Furthermore, the seal used to seal the injection port is oxidized upon contact with external oxygen. Since the temperature sensing bulb is generally made of metallic iron, oxidation forms a fluffy oxide layer, further exacerbating the loss of ethyl acetate.

[0006] Based on the above description of ethyl acetate as a temperature-sensitive medium, it has advantages in process efficiency, but shortcomings in suppressing volatility. Conventionally, to prevent leakage at the injection port, a sealant is applied to seal the port. Current technology uses dispensing machines to automate dispensing, precisely dotting, injecting, coating, or dripping the adhesive liquid onto the target location, enabling the application of dots, lines, circles, or arcs.

[0007] It should be noted that existing dispensing machines require clamps to position and hold the object to be dispensed, such as a temperature sensor, and it is necessary to ensure that the injection port of the temperature sensor is directly facing the dispensing gun. However, in actual processes, when the temperature sensor is delivered from the previous process to the current dispensing process, it is in a random state, meaning that the position of its injection port is arbitrary.

[0008] Currently, calibration is mainly done manually, but this is inefficient. Alternatively, a special structural design can be used for the temperature sensing bulb. After the temperature sensing bulb is clamped and positioned on the dispensing machine, its injection port is positioned directly opposite the injection gun. However, in actual processes, the temperature sensing bulb is generally designed as a column. In this case, designing the injection port at the axis is a feasible solution. However, considering that the temperature sensing bulb needs to be installed inside the temperature control head, the temperature sensing bulb is generally designed as a boss. Referring to the published patent CN115076450A, a quick-connect temperature control head that can block heat conduction, in order to avoid displacement output components such as output sleeves, the injection port is located on the stepped ring surface of the temperature sensing bulb. In this case, it is impossible to achieve the clamping and positioning of the temperature sensing bulb, i.e., to ensure that the position of the injection port is directly opposite the injection gun, through structural design.

[0009] That is, for the rotating temperature sensing bulb represented by the above-mentioned boss-shaped structure, how to automatically inject liquid into the temperature sensing bulb with the injection port on the stepped annular surface is the technical problem to be solved by the present invention.

[0010] During the manufacturing process, compliance procedures are performed on the temperature sensing bag, such as engraving the production date and product model onto it to facilitate traceability and quality identification. This can be achieved using conventional laser marking technology. However, the problem lies in the fact that for temperature sensing bags with the aforementioned structural characteristics, the marking position is not arbitrary; the marking can only be placed on the raised platform or stepped annular surface, and cannot be simultaneously engraved in segments on different surfaces. It is important to note that the temperature sensing bag has a small volume, especially its cross-sectional area, and its raised platform area is limited. When markings containing dates and model numbers are engraved on it, the font is small and difficult to read.

[0011] The present invention engraves the marking in an arc shape on the ring surface, which is a good way to make the marking recognizable by straight pipe. As mentioned above, the injection port is also set on this ring surface, which necessarily requires the marking position to avoid the injection port. Therefore, how to avoid the injection port on the ring surface to achieve automated marking is another technical problem to be solved by the present invention. Summary of the Invention

[0012] In response to the problems raised in the background art, the present invention provides a machine vision-based dispensing and marking method to solve them, and the present invention will be further described below.

[0013] A machine vision-based dispensing and marking method is used to dispense and mark a temperature sensing bag, wherein the temperature sensing bag has a boss-shaped rotating structure and the injection port is located on a ring-shaped step; the method includes the following steps:

[0014] A certain number of temperature-sensing bags are placed on the conveyor belt with the injection port facing upwards and move in one direction with the conveyor belt.

[0015] After entering the image acquisition range of the first image acquisition unit, the conveyor belt stops, and the first image acquisition unit acquires the image information within the range and transmits it to the visual positioning system.

[0016] The visual positioning system recognizes and calculates images, establishes a parameter list, and stores it at the geometric center of the temperature sensing bag and the position of the injection port under the dispensing and marking positions;

[0017] The dispensing machine moves according to the parameter list feedback control and dispenses glue to the injection port in sequence. After the dispensing is completed, the conveyor belt starts and moves the temperature sensing bag a predetermined distance to the marking position and stops. The laser head starts and rotates and / or moves according to the parameter list so that the marking area avoids the injection port and completes the marking operation in sequence.

[0018] Furthermore, the conveyor belt and the temperature-sensing bag have a significant color difference, which is intended to allow for rapid and accurate identification by the visual positioning system.

[0019] Furthermore, the temperature sensing packs placed in batches are stored in a set order, and their geometric center coordinates are stored sequentially. The geometric center coordinates are matched with the coordinates of the nearest injection port to them as the dispensing position feature parameters of the current temperature sensing pack. The parameter list also includes the marking position feature parameters corresponding to the dispensing position feature parameters. The marking position feature parameters are obtained by superimposing a predetermined distance on the dispensing position feature parameters.

[0020] Furthermore, the markings are engraved on the stepped ring surface, and a fan-shaped marking area is generated based on the input diameter of the temperature sensing bulb boss and the main body diameter. The width of the area is the height of the font, and the center of the circle is concentric with the geometric center coordinate of the marking position.

[0021] Engraving methods include:

[0022] Based on the geometric center coordinates of the marking position according to the marking position feature parameters, control the laser head to translate to above the center of the first stored temperature sensing bag;

[0023] Determine whether the coordinates of the injection port corresponding to the current temperature sensing bag are within the marking area. If not, perform the marking operation within the current marking area. If it is within the marking area, start the laser head to rotate an angle toward the injection port to avoid the position.

[0024] The laser head is activated to imprint the markings onto the raised ring surface. The above steps are repeated to imprint the markings onto the temperature sensing bulb in sequence.

[0025] Optionally, the method for avoiding the injection port in the marking area is as follows: obtain the center coordinates of the marking area and the central angle α of the sector area; combine the geometric center coordinates of the marking position and the coordinates of the injection port of the marking position to calculate the angle value β with the geometric center coordinates of the marking position as the vertex; if α / 2 < β, it is determined that the injection port is outside the marking area and the marking operation is performed; if α / 2 ≥ β, it is determined that the injection port is within the marking area, and the rotating device drives the laser head to rotate by a constant angle δ, and δ > α / 2 - β.

[0026] Optionally, the method for avoiding the injection port by the marking area is as follows: obtain the center coordinates of the marking area, combine the geometric center coordinates of the marking position and the injection port coordinates of the marking position, calculate the angle value β with the geometric center coordinates of the marking position as the vertex, and drive the laser head to rotate in a direction different from the injection port of the marking position with a rotation angle of π-β, so that the coordinates of the marking area and the coordinates of the injection port of the marking position are symmetrical about the combined geometric center coordinates of the marking position.

[0027] Furthermore, a second image acquisition unit is set before the laser head to acquire the actual coordinates of the geometric center of the temperature sensing bag stationary on the marking position, and calculate the position offset difference between the geometric center coordinates of the temperature sensing bag and the marking position in the list in terms of the transmission method; when the position offset difference is less than a preset value, it is determined that the marking area is still on the boss ring surface and the marking operation is performed; otherwise, the marking operation is not performed.

[0028] Furthermore, the batch of temperature-sensing packets are placed discretely or clustered on the conveyor belt; the actual coordinates of the geometric center of the marking position with a position offset difference exceeding a preset value are updated to the geometric center coordinates of the marking position in the list, and the corresponding laser head rotation angle parameter column is updated simultaneously. The laser head completes the marking operation sequentially according to the updated parameters.

[0029] Beneficial effects: Compared with the prior art, the present invention integrates the dispensing and marking operations into one step, uses machine vision to identify the position of the temperature sensing bag, and the temperature sensing bag has a specific stepped shape. The injection port is set on the stepped ring surface, and the mark is engraved in an arc shape on the stepped ring surface, avoiding the injection port. Attached Figure Description

[0030] Figure 1 : Flowchart of the method of the present invention;

[0031] Figure 2 Top view of the temperature sensing bulb structure to which the method of the present invention applies;

[0032] Figure 3 : A schematic diagram showing the temperature sensing bag passing through the dispensing and marking positions sequentially via a conveyor belt;

[0033] Figure 4 : A list of stored data about the characteristic parameters of the temperature sensing bag;

[0034] Figure 5 : A schematic diagram illustrating how the marking area avoids the injection port using Method 1;

[0035] Figure 6 : A schematic diagram illustrating how the marking area avoids the injection port using Method 2;

[0036] Figure 7 : The displacement of the temperature sensing bulb relative to the conveyor belt causes the marking area to shift on the stepped ring surface.

[0037] Figure 8 A schematic diagram illustrating how the displacement of the temperature sensor relative to the conveyor belt causes errors in the temperature sensor. Detailed Implementation

[0038] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

[0039] A machine vision-based dispensing and marking method is provided for automating the dispensing and marking operations on a temperature sensing package. The temperature sensing package targeted in this invention has a rotating boss structure. (See attached diagram.) Figure 2 The internal temperature-sensitive medium is ethyl acetate liquid, and the injection port is located on the ring-shaped step. The dispensing operation involves applying sealant to the injection port to seal and prevent corrosion, while the marking operation involves using a laser marking machine to engrave at least the date and model information onto the ring surface of the temperature-sensing bulb.

[0040] This method automates the operation. The temperature-sensing bag is placed on a conveyor and travels unidirectionally, passing sequentially through a dispensing machine and a marking machine positioned to the side of the conveyor, undergoing dispensing and marking operations in sequence. Furthermore, an image acquisition unit, such as a panoramic camera, is installed above the conveyor for image acquisition. The acquired image information is transmitted to a CCD vision positioning system connected to the system. An algorithm automatically identifies the temperature-sensing bag in the image, guiding the dispensing and marking machines to perform the dispensing and marking operations.

[0041] Reference Appendix Figure 1 The dispensing and marking method includes:

[0042] A certain number of temperature-sensing bags are placed on the conveyor belt with the injection port facing upwards, and move with the conveyor belt;

[0043] After the temperature sensing bag enters the image acquisition range of the first image acquisition unit, the conveyor belt stops, and the first image acquisition unit acquires the image information within the range and transmits it to the visual positioning system.

[0044] The visual positioning system recognizes and calculates images, locates and stores the geometric center of all temperature sensing bags, the position of the injection port, and the positional correspondence of the injection port relative to the geometric center. The feedback control moves the nozzle of the dispensing machine downwards to align with the injection port in sequence, and the dispensing machine starts to dispense glue to the injection port in sequence.

[0045] The conveyor belt starts and travels a predetermined distance s before reaching the laser head. The laser head starts and rotates and / or moves according to its positional relationship, so that the marking area avoids the liquid injection port, and the marking operation is completed on the marking area.

[0046] In the above method steps, when the temperature sensing bag is placed on the conveyor belt, the liquid injection port on the temperature sensing bag should face upwards. Based on the structural characteristics of the rotating body of the temperature sensing bag boss, its center of gravity is close to the conveyor belt, and it is in a stable and anti-tipping state. At the same time, this method requires the conveyor belt to transport the temperature sensing bag slowly at a low speed, in order to avoid relative displacement between the temperature sensing bag and the conveyor belt during transport.

[0047] For temperature-sensing packets scattered on the conveyor belt, which are in a clustered state, as many temperature-sensing packets as possible can be placed within the limited image acquisition range of the first image acquisition unit. At the same time, the temperature-sensing packets in the clustered state have a mutual limiting effect, maintaining a relatively stationary state between the temperature-sensing packets and the conveyor belt. For temperature-sensing packets placed on tooling fixtures, the fixtures are placed directly on the conveyor belt to maintain a relatively stationary state with respect to the conveyor belt. The present invention does not limit the placement method of the temperature-sensing packets.

[0048] The first image acquisition unit is used to acquire images of the temperature sensing pack within the image acquisition range. The acquired images are processed by the visual positioning system to identify the position coordinates of the geometric center of the temperature sensing pack and the injection port. The acquired coordinate data is stored in the storage unit.

[0049] In this method, the temperature-sensing bag is generally made of iron or stainless steel, and the conveyor belt carrying it has a significant color difference from it. The edge of the temperature-sensing bag also has a significant color difference from the conveyor belt, aiming to enable rapid and accurate identification by the visual positioning system. The image acquired by the first image acquisition unit is processed and fitted to obtain the curve equation of the boundary circle and the injection port. The coordinates of the center point represent the absolute position of the temperature-sensing bag and its injection port.

[0050] Reference Appendix Figure 3In this method, the number of temperature-sensing packs for dispensing and marking is not limited to one. The identification and storage of temperature-sensing packs within the image acquisition range relies on a set order, such as using the direction of travel (Y direction) as the first priority and the direction perpendicular to the direction of travel (X direction) as the second priority. The temperature-sensing packs are identified sequentially, and their corresponding geometric center and injection port position coordinates are listed and stored. After identifying the coordinates of all temperature-sensing pack centers and injection ports, the first image acquisition unit determines the correspondence between the coordinates. Undoubtedly, the distance from the injection port to the nearest temperature-sensing pack center must be less than the temperature-sensing pack diameter. Based on this, while sequentially storing the center of the temperature-sensing pack dispensing position, the coordinates of the current temperature-sensing pack dispensing position center and its nearest dispensing injection port are matched as the feature parameters of the current temperature-sensing pack.

[0051] The dispensing head is mounted on a three-axis (X, Y, Z) robotic arm. Based on the acquired coordinates of the dispensing position at the injection port, the three-axis robotic arm controls the dispensing head to move sequentially to the injection port to complete the dispensing. Based on the priority relationship of the stored information, dispensing is performed in the corresponding order. For the three-axis robotic arm, the X and Y axes control the dispensing head to move sequentially according to the stored order of the dispensing position center of the temperature sensing bulb, while the Z axis controls the raising and lowering of the dispensing head to avoid collisions with the temperature sensing bulb protrusion, ensuring the dispensing head is close to the injection port during the dispensing operation.

[0052] After dispensing is completed, the conveyor belt travels a predetermined distance, then transports the temperature-sensing pack to a stop under the laser head. This distance is constant. Based on this constant distance, the stored data list of characteristic parameters of the temperature-sensing pack includes the coordinates of the marking position corresponding to the temperature-sensing pack. In this method, the conveying direction is set to be unidirectional with no significant slippage between the conveyor and the temperature-sensing pack. The X-axis parameter of the temperature-sensing pack is superimposed with the predetermined distance to obtain the marking position coordinates. Based on these marking position coordinates, it can be predicted whether the current marking area is located on the surface of the temperature-sensing pack.

[0053] This method performs dispensing and marking operations simultaneously while batch-transmitting temperature-sensing packs. The common exposed outer surfaces for marking of all temperature-sensing packs are the stepped annular surface and the top surface of the boss.

[0054] In one embodiment 1, the mark is engraved on the top surface of the boss. The engraving method is as follows: based on the geometric center coordinates of the mark position in the obtained mark position coordinates and the input geometric parameters of the temperature sensing bag including the diameter of the boss, the laser head is controlled by a three-axis robot to move sequentially to the top of the center of the temperature sensing bag according to the storage order of the temperature sensing bags, and the mark is laser engraved on the top surface of the boss.

[0055] In this embodiment, the laser head only has translational freedom and is not related to the position of the injection port. The marking and positioning are easy to achieve, but the marking range is small. It cannot mark long marks in a single line, and even if multiple lines are marked or the marking is curved, the font size is not easy to distinguish intuitively.

[0056] Furthermore, the present invention also provides an embodiment 2, wherein the marking is engraved on the stepped ring surface, and the engraving method is as follows:

[0057] Based on the geometric center coordinates of the marked position in the obtained marked position coordinates, the laser head is translated to the center of the first stored temperature sensing bag by the control of a three-axis robot arm;

[0058] Based on the input geometric parameters of the temperature sensor, including the diameter of the boss and the diameter of the temperature sensor body, a marking area is generated. The marking area is fan-shaped, with a width equal to the height of the font, and the center of the circle is concentric with the geometric center coordinate of the marking position.

[0059] Determine whether the corresponding marking position injection port coordinates are within the marking area. If not, perform the marking operation within the current marking area. If within the marking area, start the laser head to rotate an angle toward the injection port to avoid the position.

[0060] The laser head is activated to imprint the markings onto the raised ring surface. The above steps are repeated to imprint the markings onto the temperature sensing bulb in sequence.

[0061] In this embodiment, the laser head is mounted on a rotating device. The rotating device controls the rotation of the laser head to perform the avoidance operation of the marking area on the injection port. This embodiment provides the following two avoidance methods.

[0062] Method 1: Refer to the appendix Figure 5 The center coordinates of the marking area and the central angle α of the sector area are obtained. Combining the geometric center coordinates of the marking position and the liquid injection port coordinates of the marking position, the angle value β with the geometric center coordinates of the marking position as the vertex is calculated. If α / 2 < β, it is determined that the liquid injection port is outside the marking area and the marking operation is performed. If α / 2 ≥ β, it is determined that the liquid injection port is within the marking area. The rotating device drives the laser head to rotate a constant angle δ, and δ > α / 2 - β.

[0063] In this avoidance method, the distance between the engraved mark and the injection port is random. After the laser head is moved to above the center of any temperature sensing bulb, if the injection port is outside the marking area, the marking operation is performed directly, and the distance between the mark and the injection port is random. If the injection port is within the marking area, an avoidance operation is performed before the marking operation, and the mark is adjacent to the injection port. This avoidance method does not perform an avoidance operation on all temperature sensing bulbs, resulting in a high marking speed.

[0064] Method 2: See attached document Figure 6The center coordinates of the marking area are obtained. Combined with the geometric center coordinates of the marking position and the liquid injection port coordinates of the marking position, the angle value β with the geometric center coordinates of the marking position as the vertex is calculated. The laser head is driven to rotate in a direction different from the liquid injection port with π-β as the rotation angle δ, so that the coordinates of the marking area and the liquid injection port coordinates of the marking position are symmetrical about the combined geometric center coordinates of the marking position.

[0065] Under this avoidance method, all temperature sensing bags are subjected to avoidance operation, and the printed mark is placed at the countermeasure position of the injection port. That is, the marking area always has a constant positional relationship with the injection port. Compared with the first method, the injection port is not adjacent to the marking area in this method, and the sealant tail cannot be adhered to the mark after the glue is received.

[0066] Regardless of the avoidance method, the laser head must possess translational and rotational degrees of freedom. When sequentially etching the temperature sensing elements, the acquired rotational angle parameters are obtained after the first image acquisition unit identifies and calculates the position parameters of all temperature sensing elements, and can be calculated before the laser head etches the markings. This allows for a large etching range, making it particularly suitable for single-line etching of long markings, which is easily and intuitively identifiable.

[0067] In this method, the conveyor belt starts intermittently and stops during dispensing and marking, aiming to ensure that the first image acquisition unit can clearly capture images of the temperature-sensing packs placed on the conveyor belt in batches. Common sense dictates that the moment the conveyor belt stops and starts abruptly is the moment when the temperature-sensing packs are most likely to slide relative to the conveyor belt. For temperature-sensing packs loaded with tooling, their position remains unchanged; however, for temperature-sensing packs placed directly, there is a possibility of slight displacement.

[0068] Based on this, the method also sets a second image acquisition unit before the laser head to obtain the actual position parameters of the temperature sensing bag stationary at the marking position, including the geometric center coordinates of the marking position. Based on the actual coordinates of the geometric center of the marking position, the marking position coordinates obtained by the position translation conversion obtained by the first image acquisition unit in the list can be checked, thereby providing a basis for judging whether the marking area exceeds the step ring surface.

[0069] Reference Appendix Figure 7 Given that the conveyor belt in this method is driven in one direction only, even if the temperature sensing bag slides relative to the conveyor belt, there is no rotation. Therefore, this method can determine whether to perform the marking operation based solely on the offset value of the temperature sensing bag's center coordinates: The second image acquisition unit obtains the actual coordinates of the geometric center of the marking position of the temperature sensing bag stationary at the marking position, and calculates the position offset difference s between the geometric center coordinates of the marking position and the geometric center coordinates of the marking position in the list on the conveyor belt (X-axis); when the position offset difference s is less than the preset value S, it is determined that the marking area is still on the boss ring surface, and the marking operation is performed; otherwise, the marking operation is not performed.

[0070] The preset value for comparison with the position offset difference can be set according to the height A of the label font and the obtained diameter d of the temperature sensing bulb boss and the diameter D of the main body: set the theoretical position of the label to the center of the toroidal surface, that is, at this time the preset value S = ((Dd) / 2-A) / 2.

[0071] To maintain the relative stillness between the temperature sensing bulb and the conveyor belt, this method includes selecting a conveyor belt with a high coefficient of friction, reducing the transmission speed of the conveyor belt, and replacing the conveyor belt before local wear occurs.

[0072] Reference Appendix Figure 8 When the temperature sensors are placed discretely on the conveyor belt, the temperature sensors that experience sliding displacement are random, and when the sliding displacement exceeds a preset value, such as G... K It should be noted that the actual order of the temperature sensors may differ from the order in the list, i.e., temperature sensor G... K Move to G K-1 Subsequently, the marking order of the two temperature sensors becomes out of order, but this only applies to the current two sensors and has no impact on the marking of other sensors. Preferably, the temperature sensors are placed in batches and clustered together on the conveyor belt, aiming to eliminate sliding displacement of the sensors by having them abut against each other. In this case, even if sliding occurs, it will only happen at the head and tail of the sensor in the direction of travel.

[0073] Based on the aforementioned instances where displacement exceeds the preset value and the actual situation where displacement causes misordering of adjacent temperature sensors, this method can provide special handling for these temperature sensors whose marking areas extend beyond the boss ring surface and the misordered temperature sensors caused by the displacement: the actual coordinates of the geometric center of the marking position with a position offset difference exceeding the preset value are updated to the geometric center coordinates of the marking position in the list, and the corresponding laser head rotation angle parameter column is updated simultaneously. The laser head then completes the marking operation sequentially according to the updated parameters.

[0074] With the local calibration update of this method, the computing power requirement of the system is greatly reduced. Most of the data can be used in both dispensing and marking operations after being acquired once. If the marking area exceeds the step ring surface, only the position of the exceeding temperature sensing bag needs to be calibrated. Even if the temperature sensing bags are out of order, only the adjacent temperature sensing bags that are out of order need to be calibrated. When the order is out of order, the marking order of the temperature sensing bags does not correspond one-to-one with the dispensing order, but the marking operation can be completed without omission.

[0075] The data acquired by the second image acquisition unit in this method is used to calibrate part of the data acquired by the first image acquisition unit. That is, the second image acquisition unit and the first image acquisition unit are connected in data. However, in an extreme embodiment, the second image acquisition unit can be independent of the data of the first image acquisition unit, and the second image acquisition unit performs the same operation as the first image acquisition unit.

[0076] This invention integrates dispensing and marking operations into one step. The temperature sensing pack is located using machine vision. The temperature sensing pack has a specific stepped shape. The injection port is set on the stepped ring surface, and the marking is engraved in an arc shape on the stepped ring surface, avoiding the injection port.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A machine vision-based dispensing and marking method for dispensing and marking temperature sensing bags, wherein the temperature sensing bag has a boss-shaped rotating structure and the injection port is located on a ring-shaped step; characterized in that, Includes the following steps: A certain number of temperature-sensing bags are placed on the conveyor belt with the injection port facing upwards and move in one direction with the conveyor belt. After entering the image acquisition range of the first image acquisition unit, the conveyor belt stops, and the first image acquisition unit acquires the image information within the range and transmits it to the visual positioning system. The visual positioning system recognizes and calculates images, establishes a parameter list, and stores it at the geometric center of the temperature sensing bag and the position of the injection port under the dispensing and marking positions; The dispensing machine moves according to the parameter list feedback control and dispenses glue to the injection port in sequence. After the dispensing is completed, the conveyor belt starts and moves the temperature sensing bag a predetermined distance to the marking position and stops. The laser head starts and rotates and / or moves according to the parameter list so that the marking area avoids the injection port and the marking operation is completed in sequence. The temperature sensing packs placed in batches are stored in a set order, and their geometric center coordinates are stored sequentially. The geometric center coordinates are matched with the coordinates of the nearest injection port to them, which are used as the dispensing position feature parameters of the current temperature sensing pack. The parameter list also includes marking position feature parameters corresponding to the dispensing position feature parameters. The marking position feature parameters are obtained by superimposing a predetermined distance on the dispensing position feature parameters. The markings are engraved on the stepped ring surface. A fan-shaped marking area is generated based on the input diameter of the temperature sensing bulb protrusion and the main body diameter. The width of the area is the height of the font, and the center of the circle is concentric with the geometric center coordinate of the marking position. Engraving methods include: Based on the geometric center coordinates of the marking position according to the marking position feature parameters, control the laser head to translate to above the center of the first stored temperature sensing bag; Determine whether the coordinates of the injection port corresponding to the current temperature sensing bag are within the marking area. If not, perform the marking operation within the current marking area. If it is within the marking area, start the laser head to rotate an angle toward the injection port to avoid the position. The laser head is activated to imprint the markings onto the raised ring surface. The above steps are repeated to imprint the temperature sensing bulb in sequence. The method for avoiding the injection port in the marking area is as follows: Obtain the center coordinates of the marking area and the central angle α of the sector area; Combine the geometric center coordinates of the marking position and the coordinates of the injection port at the marking position, calculate the angle value β with the geometric center coordinates of the marking position as the vertex. If α / 2 < β, it is determined that the injection port is outside the marking area, and the marking operation is performed; if α / 2 ≥ β, it is determined that the injection port is within the marking area, and the rotating device drives the laser head to rotate by a constant angle δ, where δ > α / 2 - β. The method to avoid the injection port in the marking area is as follows: obtain the center coordinates of the marking area, combine the geometric center coordinates of the marking position and the injection port coordinates of the marking position, calculate the angle value β with the geometric center coordinates of the marking position as the vertex, and drive the laser head to rotate in a direction different from the injection port of the marking position with a rotation angle of π-β, so that the coordinates of the marking area and the coordinates of the injection port of the marking position are symmetrical about the combined geometric center coordinates of the marking position. A second image acquisition unit is set before the laser head to acquire the actual coordinates of the geometric center of the marking position of the temperature sensing bag stationary on the marking position, and calculate the positional offset difference between the geometric center coordinates of the marking position and the geometric center coordinates of the listed marking positions in the transmission method; when the positional offset difference is less than the preset value, it is determined that the marking area is still on the boss ring surface and the marking operation is performed; otherwise, the marking operation is not performed. The default value is ((Dd) / 2-A) / 2; where A is the height of the label font, d is the diameter of the temperature sensor boss, and D is the diameter of the temperature sensor body. The batch of temperature-sensing packets are placed discretely or clustered on the conveyor belt; the actual coordinates of the geometric center of the marking position with a position offset difference exceeding the preset value are updated to the geometric center coordinates of the marking position in the list, and the corresponding laser head rotation angle parameter column is updated simultaneously. The laser head completes the marking operation sequentially according to the updated parameters.

2. The dispensing and marking method according to claim 1, characterized in that: The conveyor belt and the temperature sensing bag have a significant color difference.

Images