Laser cutting head zero focus test method based on reflected light detection

Abstract

The invention relates to the technical field of focus testing, and particularly discloses a laser cutting head zero focus testing method based on reflected light detection, which comprises the following steps: S1, acquiring an optical signal reflected by a processed plate in a cutting process; s2, adjusting the position of a focusing lens to enable a laser focus to move along the optical axis direction relative to the surface of the plate; s3, recording reflected light intensity values corresponding to different focus positions, obtaining a function relationship between the reflected light intensity and the focus positions, and drawing a light intensity-focus position relationship curve; s4, determining a corresponding focus position when the intensity of the reflected light reaches the maximum value as an optical zero focus position of the system; s5, automatically recording and storing an optical zero focus position; the reflected light detector arranged in the cutting head or the laser reads the intensity of the reflected light in the cutting process, the function relation between the focus position and the intensity of the reflected light can be established, and the focus position corresponding to the maximum value of the intensity of the reflected light is the most accurate optical zero focus position.

Description

Technical Field

[0001] The invention belongs to the technical field of focus testing, and in particular relates to a zero-focus testing method for a laser cutting head based on reflected light detection. Background Art

[0002] In the field of laser cutting technology, accurately determining the optical zero focus position of the laser cutting head is one of the key factors to ensure cutting quality and efficiency. However, the existing technology has obvious shortcomings in this regard. Traditional zero focus test methods often rely on manual observation and manual adjustment, which is not only time-consuming and labor-intensive, but also easily affected by human errors, resulting in a significant reduction in the accuracy and reliability of the test results. In addition, these methods usually lack real-time and intelligence, and cannot dynamically adjust the laser focus position according to the actual reflection of the processed plate, thereby limiting the further improvement of cutting accuracy.

[0003] In view of these shortcomings, the industry urgently needs a more accurate, efficient and automated method for testing the zero focus of laser cutting heads. This new method should be able to obtain the light signals reflected by the processed plate in real time and intelligently adjust the laser focus position according to these signals to achieve accurate measurement of the optical zero focus position.

[0004] In view of this, the inventors proposed a laser cutting head zero focus test method based on reflected light detection to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a laser cutting head zero focus test method based on reflected light detection to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A laser cutting head zero focus test method based on reflected light detection, comprising:

[0008] S1, obtaining the light signal reflected by the processed plate during the cutting process;

[0009] S2. According to the optical signal, the laser is set to a low energy output mode, and the position of the focusing lens is gradually adjusted so that the laser focus moves along the optical axis relative to the surface of the plate;

[0010] S3, recording the reflected light intensity values ​​corresponding to different focal positions, obtaining the functional relationship between the reflected light intensity and the focal position, and drawing a light intensity-focal position relationship curve;

[0011] S4, determining the focal position corresponding to when the reflected light intensity reaches the maximum value as the optical zero focus position of the system;

[0012] S5. Automatically record and save the optical zero focus position for subsequent calibration or optimization of the laser cutting system.

[0013] Preferably, the reflected light sensor is at least one of a single-band light sensor and a multi-band light sensor, and is used to detect the reflected light intensity of lasers with different wavelengths.

[0014] Preferably, the optical lens group in the cutting head is at least one of a single group of lenses and multiple groups of lenses.

[0015] Preferably, the functional relationship between the reflected light intensity and the focal position is expressed as:

[0016]

[0017] I r: reflected light intensity, unit: W / m 2 , which is read by the sensor;

[0018] d: The displacement of the laser focus relative to the plate surface, unit: mm, generated by the movement of the focusing lens;

[0019] f(d): Functional relationship between reflected light intensity and focal displacement;

[0020] I0: Maximum value of reflected light intensity, unit: W / m 2 ;

[0021] σ: standard deviation of light intensity distribution, determines the distribution range of the spot size, unit: mm;

[0022] d0: zero focus position, that is, the focus position corresponding to when the reflected light intensity Ir reaches the maximum value;

[0023] d-d0: The distance the focus deviates from the zero focus position, unit: mm.

[0024] Preferably, the optical zero focus position is determined by the following formula:

[0025]

[0026] d0: zero focus position, that is, the focus position corresponding to when the reflected light intensity Ir reaches the maximum value.

[0027] Preferably, the optical signal is obtained by arranging a reflection light sensor inside the cutting head or the laser to read the optical signal.

[0028] Preferably, the signal of the reflected light sensor is normalized to obtain an accurate light signal, and the expression of the normalization is:

[0029]

[0030] Among them, I norm : Normalized reflected light intensity value;

[0031] I min and I r max : Minimum and maximum values ​​of reflected light intensity.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention can establish a functional relationship between the focal position and the reflected light intensity by reading the reflected light intensity during the cutting process through a reflected light detector arranged in the cutting head or inside the laser, wherein the focal position corresponding to the maximum reflected light intensity is the most accurate optical zero focus position. This test method is convenient and reliable, and has high measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of a zero-focus test method for a laser cutting head based on reflected light detection;

[0035] Figure 2 This is a light intensity-focus position curve diagram in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Embodiment 1:

[0038] See also Figure 1 and Figure 2 As shown, a laser cutting head zero focus test method based on reflected light detection includes:

[0039] S1, obtaining the light signal reflected by the processed plate during the cutting process;

[0040] S2. According to the optical signal, the laser is set to a low energy output mode, and the position of the focusing lens is gradually adjusted so that the laser focus moves along the optical axis relative to the surface of the plate;

[0041] S3, recording the reflected light intensity values ​​corresponding to different focal positions, obtaining the functional relationship between the reflected light intensity and the focal position, and drawing a light intensity-focal position relationship curve;

[0042] S4, determining the focal position corresponding to when the reflected light intensity reaches the maximum value as the optical zero focus position of the system;

[0043] S5. Automatically record and save the optical zero focus position for subsequent calibration or optimization of the laser cutting system.

[0044] As can be seen from the above, by reading the reflected light intensity during the cutting process through a reflected light detector arranged in the cutting head or inside the laser, a functional relationship between the focal position and the reflected light intensity can be established, where the focal position corresponding to the maximum reflected light intensity is the most accurate optical zero focus position. This test method is convenient and reliable, and has high measurement accuracy.

[0045] Embodiment 2:

[0046] The reflected light sensor is a single-band light sensor used to detect the reflected light intensity of lasers with different wavelengths.

[0047] Specifically, the optical lens group in the cutting head is a single group of lenses, and the optical lens group complies with the principle of optical path reversibility.

[0048] Specifically, the functional relationship between the reflected light intensity and the focal position is expressed as follows:

[0049]

[0050] I r: reflected light intensity, unit: W / m 2 , which is read by the sensor;

[0051] d: The displacement of the laser focus relative to the plate surface, unit: mm, generated by the movement of the focusing lens;

[0052] f(d): Functional relationship between reflected light intensity and focal displacement;

[0053] I0: Maximum value of reflected light intensity, unit: W / m 2 ;

[0054] σ: standard deviation of light intensity distribution, determines the distribution range of the spot size, unit: mm;

[0055] d0: zero focus position, that is, the focus position corresponding to when the reflected light intensity Ir reaches the maximum value;

[0056] d-d0: The distance the focus deviates from the zero focus position, unit: mm.

[0057] Specifically, the optical zero focus position is determined by the following formula:

[0058]

[0059] d0: zero focus position, that is, the focus position corresponding to when the reflected light intensity Ir reaches the maximum value.

[0060] Specifically, the optical signal is obtained by setting a reflective light sensor inside the cutting head or the laser to read the optical signal.

[0061] Specifically, the signal of the reflected light sensor is normalized to obtain an accurate light signal, and the expression of the normalization process is:

[0062]

[0063] Among them, I norm : Normalized reflected light intensity value;

[0064] I min and I r max : Minimum and maximum values ​​of reflected light intensity.

[0065] From the above, it can be seen that by directly obtaining the light signals reflected by the processed plate during the cutting process and intelligently adjusting the laser focus position based on these signals, this method can record and analyze the relationship between the reflected light intensity and the focus position in real time, so as to accurately find the focus position corresponding to the maximum reflected light intensity, that is, the optical zero focus. This process not only avoids the human errors that may be introduced in traditional methods, but also significantly improves the test efficiency and accuracy. In addition, the automatically recorded and saved optical zero focus position information provides reliable data support for the subsequent calibration or optimization of the laser cutting system, which helps to improve the overall cutting quality and production efficiency;

[0066] By detecting the maximum value of the reflected light intensity, which directly corresponds to the optical zero focus position, the subjective error in the traditional focusing method is eliminated, and the functional relationship between the reflected light intensity and the focus displacement is established, which is theoretically applicable to different types of lasers and cutting heads;

[0067] The intensity of reflected light presents a Gaussian distribution characteristic, which is highly consistent with the energy distribution law of the optical system. The Gaussian distribution model can effectively predict the impact of focus offset on reflected light, providing a theoretical basis for the design and optimization of the optical system. Multiple experiments have verified the consistency of the zero focus position, and the results are stable and reliable, proving the repeatability and robustness of the method.

[0068] The focusing lens position is automatically adjusted and data is recorded in real time without manual intervention, which reduces the complexity of operation and shortens the test process. The calibration can be completed in just a few minutes, which improves the working efficiency of the cutting equipment.

[0069] Embodiment three:

[0070] In a certain manufacturing enterprise, laser cutting machines need to be calibrated regularly to ensure cutting quality. Through the zero focus test method based on reflected light detection described in this article, the zero focus detection and calibration of a laser cutting device is completed.

[0071] Implementation steps

[0072] 1. Equipment Preparation

[0073] Laser cutting head: a certain type of cutting head, the fiber laser output power is set to 10W (low energy mode), and the wavelength is 1064nm.

[0074] Reflected light sensor: installed inside the laser, with a single-band (1064nm) and a sampling frequency of 100Hz.

[0075] Test material: A stainless steel test plate with a flat surface, a thickness of 2mm and a surface reflectivity of approximately 60%.

[0076] Focusing lens: The movable adjustment range is ±5mm, and the step accuracy is 0.01mm.

[0077] Data acquisition system: Record the reflected light intensity through the built-in data acquisition module.

[0078] 2. Data Collection

[0079] Laser scanning: Start the laser and move the focusing lens from the initial position (-5mm) to the end position (+5mm), with each step moving 0.01mm.

[0080] Data recording: At each focal point, the reflected light intensity value is collected by the sensor and recorded as I r. Table 1 below is part of the sampling data (unit: mm, W / m 2 ):

[0081]

[0082]

[0083] Table 1

[0084] like Figure 2 As shown, curve drawing: using data to draw a relationship curve between the reflected light intensity Ir (ie, the energy coupled back to the optical fiber) and the focus displacement d (lens position z), it shows a Gaussian distribution characteristic.

[0085] 3. Determine the zero focus position

[0086] According to the formula

[0087] The focal position corresponding to the maximum value of the reflected light intensity I r is calculated to be d0 = 0.00 mm, which is the optical zero focal position.

[0088] 4. System Calibration

[0089] Record zero focus: The system stores the data of d0=0.00mm into the laser cutting machine control system and uses it as a reference for subsequent cutting tasks.

[0090] Verification consistency: Repeat the test three times, the zero focus position deviation is within ±0.01mm, and the results are consistent.

[0091] Parameter application effect

[0092] 1. Test accuracy

[0093] Accuracy analysis:

[0094] Through light intensity detection, the zero focus position error is less than ±0.01mm.

[0095] Compared with traditional manual focusing methods (error ±0.1mm), the accuracy is improved by more than 10 times.

[0096] 2. Ease of operation

[0097] The whole process is completed automatically, and the test time is about 3 minutes, saving 50% time compared with traditional methods.

[0098] 3. Improved cutting quality

[0099] After zero focus position calibration, conduct cutting experiments to observe the smoothness and verticality of the cutting edge:

[0100] The cutting edge roughness Ra was reduced to 1.2μm (originally 2.5μm).

[0101] The cutting verticality error is reduced to 0.03mm (originally 0.08mm).

[0102] 4. Device compatibility

[0103] The same test method was used and repeated on different cutting heads (Brand A and Brand B). The test results showed that the method is applicable to a variety of cutting heads without additional adjustments.

[0104] From the above, it can be seen that by accurately positioning the zero focus position, reducing the trial and error adjustment time in the cutting process, and improving equipment utilization, it is possible to reduce material waste and equipment maintenance costs due to focus offset. At the same time, the quality of cutting products is improved, and customer satisfaction with cutting services increases, bringing more business opportunities to the company. In addition, this method is suitable for lasers of different wavelengths (such as 1064nm, 532nm, 355nm), and can be widely used in industrial applications such as laser cutting, welding, and marking.

[0105] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0106] In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0107] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A laser cutting head zero focus test method based on reflected light detection, characterized in that: The following steps are involved: S1, obtaining the light signal reflected by the processed plate during the cutting process; S2. According to the optical signal, the laser is set to a low energy output mode, and the position of the focusing lens is gradually adjusted so that the laser focus moves along the optical axis relative to the surface of the plate; S3, recording the reflected light intensity values ​​corresponding to different focal positions, obtaining the functional relationship between the reflected light intensity and the focal position, and drawing a light intensity-focal position relationship curve; S4, determining the focal position corresponding to when the reflected light intensity reaches the maximum value as the optical zero focus position of the system; S5. Automatically record and save the optical zero focus position for subsequent calibration or optimization of the laser cutting system.

2. A laser cutting head zero focus test method based on reflected light detection according to claim 1, characterized in that: The reflected light sensor is at least one of a single-band light sensor and a multi-band light sensor, and is used to detect the reflected light intensity of lasers with different wavelengths.

3. The method for zero focus testing of a laser cutting head based on reflected light detection according to claim 1, characterized in that: The optical lens group in the cutting head is at least one of a single lens group and multiple lens groups.

4. The method for zero focus testing of a laser cutting head based on reflected light detection according to claim 1, characterized in that: The expression of the functional relationship between the reflected light intensity and the focal position is: Ir: reflected light intensity, unit: W / m 2 , which is read by the sensor; d: The displacement of the laser focus relative to the plate surface, unit: mm, generated by the movement of the focusing lens; f(d): Functional relationship between reflected light intensity and focal displacement; I0: Maximum value of reflected light intensity, unit: W / m 2 ; σ: standard deviation of light intensity distribution, determines the distribution range of the spot size, unit: mm; d0: zero focus position, that is, the focus position corresponding to when the reflected light intensity Ir reaches the maximum value; d-d0: The distance the focus deviates from the zero focus position, unit: mm.

5. The method for zero focus testing of a laser cutting head based on reflected light detection according to claim 1, characterized in that: The optical zero focus position is determined by the following formula: d0: zero focus position, that is, the focus position corresponding to when the reflected light intensity Ir reaches the maximum value.

6. The method for zero focus testing of a laser cutting head based on reflected light detection according to claim 1, characterized in that: The optical signal is obtained by arranging a reflection light sensor inside the cutting head or the laser to read the optical signal.

7. The method for zero focus testing of a laser cutting head based on reflected light detection according to claim 6, characterized in that: The signal of the reflected light sensor is normalized to obtain an accurate light signal, and the expression of the normalization is: Among them, Ir norm : Normalized reflected light intensity value; Ir min and Ir max : Minimum and maximum values ​​of reflected light intensity.

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