A device for detecting the smoothness of the inner wall of a hole in solid wood furniture

Abstract

The present application relates to the technical field of furniture detection, and relates to a device for detecting the smoothness of the inner wall of a hole in solid wood furniture, comprising a support and a detection unit, the support being used for arranging and adjusting the direction and angle of the detection unit, the detection unit comprising a fiber bundle probe and a main component, the fiber bundle probe being used for emitting light and receiving reflected light of the inner wall of the hole in the solid wood furniture to detect the smoothness, the fiber bundle probe comprising one emitting fiber and a plurality of receiving fibers, the emitting fiber being located at the center and the plurality of receiving fibers being uniformly distributed around the emitting fiber; the main component being connected with the fiber bundle probe and being used for providing a light source and processing reflected light signals, the main component comprising a laser diode, a programmable laser drive circuit, a MEMS micromirror array, a photodiode array and a microprocessor, the present application realizes non-contact detection through emitting and receiving light, completely avoids physical damage to the hole wall of the wood, and is particularly suitable for quality control of high-grade solid wood furniture.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of furniture detection, and more particularly, it relates to a device for detecting the smoothness of the inner wall of a hole in solid wood furniture. BACKGROUND

[0002] In the manufacturing process of solid wood furniture, the smoothness of the inner wall of the hole directly affects the assembly accuracy, durability and aesthetics. For example, if the roughness of the inner wall of the connecting hole, pin hole or screw hole does not meet the requirements, it may cause parts to loosen, assembly difficulties or increased wear over time. Therefore, the detection of the smoothness of the inner wall of the hole in solid wood furniture has become an important part of production quality control. Traditional surface roughness detection methods and techniques have been widely used for planar or external surfaces, but there are still many challenges in detecting the inner wall of the hole, especially small-diameter holes.

[0003] Common methods for detecting the smoothness of the inner wall of the hole include the following: 1) contact measurement, using a needle probe of a surface roughness meter to measure the surface profile by sliding the probe on the inner wall. However, this method is prone to scratching the wood surface in solid wood furniture, and the size of the probe limits its applicability to small-diameter holes (e.g. less than 5mm), while the operation is complex and difficult to achieve rapid detection.

[0004] 2) Optical detection, such as endoscopy or laser interferometry, which measures surface roughness through image analysis or light interference. Although this method can achieve non-contact detection, the equipment is usually expensive and bulky, not suitable for portable applications, and the detection accuracy of deep holes is limited.

[0005] 3) Pneumatic measurement, which indirectly determines the roughness by measuring the pressure change of the airflow on the inner wall, which is suitable for industrial part detection, but has poor adaptability to the porosity and non-uniformity of wood, and requires custom-made probes, increasing cost and technical difficulty.

[0006] In addition, the holes in solid wood furniture are diverse (hole diameters range from 1mm to 20mm, and hole angles vary), and existing portable detection devices usually cannot adapt to different hole angles flexibly, and lack stability in narrow spaces, resulting in inconsistent detection results or inconvenient operation. SUMMARY

[0007] Therefore, the purpose of the present application is to provide a non-contact device for detecting the smoothness of the inner wall of the hole in solid wood furniture, which overcomes the defects of the prior art that the detection method is prone to damage the wood surface, has poor applicability to small-diameter holes, and the equipment is complex and not portable.

[0008] To achieve the above purpose, the present application provides the following technical solutions:

[0009] A device for detecting the smoothness of the inner wall of a hole in solid wood furniture, comprising:

[0010] a support for positioning and adjusting the orientation and angle of the detection unit;

[0011] a detection unit comprising:

[0012] a fiber bundle probe for emitting light and receiving reflected light from the inner wall of a hole in solid wood furniture to detect smoothness, the fiber bundle probe comprising one emitting fiber and a plurality of receiving fibers, the emitting fiber being located at the center and the plurality of receiving fibers being evenly distributed around the emitting fiber;

[0013] a main body component connected to the fiber bundle probe for providing a light source and processing reflected light signals,

[0014] the main body component comprising a laser diode, a programmable laser drive circuit, a MEMS micromirror array, a photodiode array and a microprocessor.

[0015] The application further provides that the fiber bundle probe further comprises a protective cap and a protective sleeve, the protective cap being transparent, fixed to the front ends of the emitting fiber and the receiving fibers and allowing light to pass through; the protective sleeve wrapping the working parts of the emitting fiber and the receiving fibers.

[0016] The application further provides that the emitting fiber is a multi-mode fiber, and the number of the receiving fibers is six, the six receiving fibers being distributed in a regular hexagon around the emitting fiber.

[0017] The application further provides that the laser diode is optically coupled to the rear end of the emitting fiber through a first connector,

[0018] the photodiode array comprising six photodiodes, each of the photodiodes being optically coupled to the rear end of a corresponding receiving fiber through a second connector.

[0019] The application further provides that the programmable laser drive circuit is adapted to different hole diameters through hierarchical brightness adjustment, the brightness adjustment comprising:

[0020] for hole diameters of 3-5 mm, the output power being 8-20 mW;

[0021] for hole diameters of 5-10 mm, the output power being 20-30 mW;

[0022] for hole diameters of 10-20 mm, the output power being 30-50 mW;

[0023] wherein the microprocessor automatically selects a corresponding power level according to the hole diameter.

[0024] The application is further provided with: the main body part further comprises a back light monitoring unit, which acquires actual light intensity of the laser diode through an optical splitter in real time and feeds back to the microprocessor, and the microprocessor dynamically adjusts output power of the programmable laser driving circuit according to the feedback signal.

[0025] The application is further provided with: the main body part is further provided with a narrow-band optical filter and an ambient light sensing module, the narrow-band optical filter is covered on the input end of the receiving optical fiber, and the center wavelength matches the wavelength of the laser diode;

[0026] The ambient light sensing module is arranged on the side surface of the main body part, detects ambient light intensity in real time, and differentially compensates signals of the photodiode array through the microprocessor.

[0027] The application is further provided with: the microprocessor performs self-calibration signal processing, including:

[0028] According to the initial light intensity value and distribution characteristics of the receiving optical fiber, a to-be-measured aperture is calculated, and corresponding brightness and divergence angle adjustment instructions are generated;

[0029] The standard deviation of light intensity of the six receiving optical fibers is calculated, and according to the formula:

[0030] ;

[0031] The hole wall roughness Ra is calculated; wherein k is a calibration coefficient; is a correction factor based on the laser diode power P; is a receiving optical fiber light intensity standard deviation; is an initial reference standard deviation; P is an actual laser power; P0 is a reference power reference.

[0032] The application is further provided with: the support comprises a rotating joint and a fixed base, the rotating joint allows the main body part to be clamped and adjusted in an angle range of 0°-180°, and the rotating joint is rotationally connected with the fixed base through an extension rod.

[0033] The application is further provided with: the rotating joint is provided with a support part for placing the main body part.

[0034] Compared with the prior art, the application has the following beneficial effects:

[0035] The application adopts a fiber bundle probe, realizes non-contact detection through emission and reception of light, completely avoids physical damage to the wood hole wall, and is particularly suitable for quality control of high-grade solid wood furniture.

[0036] The light source brightness can be adjusted in the range of 1-50mW, the MEMS micromirror array is adopted to adjust the light beam divergence angle, and the automatic adaptation to the aperture of 3-20mm is realized.

[0037] One-key starting is supported, and adjustable supports and telescopic rods are arranged, so that the user can stably operate in different scenes, and the detection efficiency is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0038] Fig. 1 It is a structural schematic diagram of the application;

[0039] Fig. 2 It is a sectional view of the optical fiber bundle probe;

[0040] Fig. 3 It is a sectional view of the connection between the protective cap and the optical fiber bundle probe.

[0041] Support 1, detection unit 2, rotary joint 11, support part 12, telescopic rod 13, fixed base 14, optical fiber bundle probe 21, main body part 22, transmitting optical fiber 211, receiving optical fiber 212, protective cap 3, protective sleeve 4. DETAILED DESCRIPTION

[0042] REFERENCE Figs. 1 to 3 Further description is made to the embodiment of the device for detecting the smoothness of the inner wall pipe of the hole of solid wood furniture, which comprises a support 1 and a detection unit 2.

[0043] The support 1 is used for arranging and adjusting the direction and angle of the detection unit 2; the support 1 comprises a rotary joint 11 and a fixed base 14; the rotary joint 11 adopts a multi-section hinge structure, and stepless angle adjustment in the range of 0°-180° is realized through the built-in damping gear set, and the target angle can be fixed through the locking knob; the support part 12 for arranging the main body part 22 is arranged on the rotary joint 11; the rotary joint 11 is connected with the fixed base 14 through the telescopic rod 13; the telescopic rod 13 is an electric telescopic rod 13, the telescopic stroke is 10-50cm, and the telescopic rod 13 is rotatably connected with the fixed base 14 at the end; the bottom of the fixed base 14 is provided with a suction cup for fixing it on the ground, so that the workbench surface of different materials can be quickly fixed; the center of the fixed base 14 is provided with a rotating bearing, and the base is arranged on the bottom of the telescopic rod 13; the bottom surface of the base is provided with a connecting shaft connected with the rotating bearing, so that the telescopic rod 13 can rotate 360° relative to the fixed base 14.

[0044] The detection unit 2 comprises an optical fiber bundle probe 21 and a main body part 22.

[0045] The optical fiber bundle probe 21 is used for emitting light and receiving reflected light of the inner wall of the hole of the solid wood furniture to detect smoothness. The optical fiber bundle probe 21 comprises one transmitting optical fiber 211 and six receiving optical fibers 212. The transmitting optical fiber 211 is a multimode optical fiber with a core diameter of 50 μm and NA=0.22. The six receiving optical fibers 212 have a core diameter of 30 μm and are arranged in a regular hexagon (with a margin error of ≤5 μm) around the transmitting optical fiber 211. The receiving end faces are coated with an anti-reflection film.

[0046] The optical fiber bundle probe 21 further comprises a protective cap 3 and a protective sleeve 4. The protective cap 3 is made of quartz glass and is transparent. The protective cap 3 is fixed to the front ends of the transmitting optical fiber 211 and the receiving optical fibers 212 and allows light to pass through. The protective sleeve 4 covers the working portions of the transmitting optical fiber 211 and the receiving optical fibers 212. The main body 22 is connected to the optical fiber bundle probe 21 and is used to provide a light source and process reflected light signals.

[0047] The main body 22 comprises a laser diode, a programmable laser drive circuit, a MEMS micromirror array, a back light monitoring unit, a photodiode array and a microprocessor. The first connector and the second connector adopt SMA905 standard optical fiber connectors.

[0048] The MEMS micromirror array comprises 4×4 programmable mirror units. The laser divergence angle can be adjusted to 5°-30°, and the response time is <1 ms.

[0049] The back light monitoring unit samples 0.5% of the light intensity of the laser diode in real time through a beam splitter (splitting ratio 95:5) at a sampling frequency of 1 kHz, and feeds back to the microprocessor through an analog-to-digital converter.

[0050] The laser diode is optically coupled to the rear end of the transmitting optical fiber 211 through the first connector. The laser diode is a red semiconductor laser with a wavelength of 635 nm.

[0051] The photodiode array comprises six photodiodes. Each photodiode is optically coupled to the rear end of the corresponding receiving optical fiber 212 through the second connector.

[0052] The six-channel photodiode adopts TO-46 metal packaging and is connected to the receiving optical fiber 212 through an MT-RJ type array optical connector. Each channel is independently configured with a transimpedance amplifier (gain range 40-80 dB). The signal link synchronously collects six-channel light intensity data at a sampling rate of 10 kHz by a 24-bit ADC and transmits the data to the microprocessor through a digital isolator.

[0053] The programmable laser drive circuit is configured in a three-stage constant current output mode. The microprocessor triggers the switching logic according to the aperture measurement results. The programmable laser drive circuit adjusts to different apertures through hierarchical brightness adjustment. The brightness adjustment includes:

[0054] For aperture 3-5mm, output power is 8-20mW, divergence angle is 5-8°;

[0055] For aperture 5-10mm, output power is 20-30mW, divergence angle is 8-12°;

[0056] For aperture 10-20mm, output power is 30-50mW, divergence angle is 12-30°;

[0057] Wherein, the microprocessor automatically selects the corresponding power range according to the aperture size.

[0058] Backlight monitoring unit over splitter real-time acquisition of laser diode actual exit light intensity, after AD conversion input to the microprocessor PID control module, realize real-time power compensation, microprocessor according to the feedback signal dynamic adjustment of the programmable laser drive circuit output power.

[0059] Narrow band optical filter (bandwidth ±2nm, center wavelength and laser wavelength offset ≤0.5nm), covering the input end of the receiving optical fiber 212, the center wavelength and the wavelength of the laser diode match;

[0060] Ambient light sensing module is configured on the side of the main component 22, ambient light sensing module uses silicon photodiode (spectrum response range 400-1100nm), real-time detection of ambient light intensity, and through the microprocessor to the signal of photodiode array light intensity differential compensation, the light intensity differential compensation model is:

[0061]

[0062] For the effective light intensity signal after compensation, the standardized input for roughness calculation.

[0063] For the original light intensity value of the first receiving optical fiber 212 (including ambient light interference), reflecting the local reflection characteristics of the hole wall.

[0064] Ambient light attenuation factor (calibration parameter), the value range is 0.85-1.15, which represents the actual blocking rate of the protective cap 3 to the ambient light.

[0065] For the background light intensity measured by the ambient light sensor independently, provides a noise reference to realize differential compensation.

[0066] For the gain compensation coefficient of the first channel, used to offset the transmission / reception efficiency difference of each receiving channel of the optical fiber bundle.

[0067] The microprocessor performs self-calibration signal processing, which includes a self-calibration phase, i.e., baseline calibration of the receiving optical fiber 212 in an idle state, and the light intensity mean square error threshold is set to 0.5 μW;

[0068] The relationship between the hole depth D and the distance L from the fiber end face to the hole bottom is calculated by using a nonlinear regression model:

[0069]

[0070] where d is the incident light spot diameter, and θ is the laser divergence angle.

[0071] First, the light intensity differential compensation algorithm is used to eliminate environmental interference to obtain a standardized reflected light intensity signal The compensated light intensity signal is the data basis for hole depth measurement,

[0072] If If it exceeds the optimal range (e.g., > 5 mm), the spot diffusion will cause nonlinear attenuation of the surface reflected light intensity, directly affecting the accuracy of the roughness formula described above.

[0073] The standard deviation of the light intensity of the six receiving optical fibers 212 is calculated, and according to the formula:

[0074]

[0075] The hole wall roughness Ra is calculated; where k is the calibration coefficient; is a correction factor based on the laser diode power P; is the standard deviation of the light intensity of the receiving optical fiber 212; is the initial reference standard deviation; P is the actual laser power; and P0 is the reference power benchmark.

[0076] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make common changes and substitutions within the scope of the technical solutions of the present application, which should be included in the protection scope of the present application.​

Claims

1. A device for detecting the smoothness of the inner wall of a hole in a solid wood furniture, characterized in that, The application relates to a device for detecting the smoothness of the inner wall of a hole in solid wood furniture, comprising: a support for placing and adjusting the direction and angle of a detection unit; the detection unit comprises: a fiber bundle probe for emitting light and receiving reflected light of the inner wall of the hole in the solid wood furniture to detect the smoothness, the fiber bundle probe comprising one emitting fiber and a plurality of receiving fibers, the emitting fiber being located at the center and the plurality of receiving fibers being uniformly distributed around the emitting fiber; a main body component connected with the fiber bundle probe for providing a light source and processing the reflected light signal, the main body component comprising a laser diode, a programmable laser drive circuit, a MEMS micromirror array, a photodiode array and a microprocessor, the emitting fiber being a multimode fiber, the number of receiving fibers being six, and the six receiving fibers being distributed in a regular hexagon around the emitting fiber; the main body component further comprising a back light monitoring unit for acquiring the actual emission light intensity of the laser diode in real time through an optical splitter and feeding back to the microprocessor, the microprocessor dynamically adjusting the output power of the programmable laser drive circuit according to the feedback signal; the microprocessor performing self-calibration signal processing, comprising: calculating the to-be-detected aperture according to the initial light intensity value and distribution characteristics of the receiving fibers and generating corresponding brightness and divergence angle adjustment instructions; calculating the standard deviation of the light intensity of the six receiving fibers and according to the formula: the fiber bundle probe further comprising a protective cap and a protective sleeve, the protective cap being transparent, being fixed to the front ends of the emitting fiber and the receiving fibers and allowing light to pass through; the protective sleeve wrapping the working parts of the emitting fiber and the receiving fibers; the laser diode being optically coupled with the rear end of the emitting fiber through a first connector, the photodiode array comprising six photodiodes, each of the photodiodes being optically coupled with the rear end of the corresponding receiving fiber through a second connector; the programmable laser drive circuit being adapted to different apertures through hierarchical brightness adjustment, the brightness adjustment comprising: for an aperture of 3-5 mm, the output power being 15-20 mW; for an aperture of 5-10 mm, the output power being 5-20 mW; for an aperture of 10-20 mm, the output power being 20-50 mW; wherein the microprocessor automatically selects the corresponding power level according to the aperture size; the main body component further being provided with a narrowband optical filter and an ambient light sensing module, the narrowband optical filter being covered on the input end of the receiving fiber, the center wavelength matching the wavelength of the laser diode; the ambient light sensing module being arranged on the side of the main body component, detecting the ambient light intensity in real time and differentially compensating the signals of the photodiode array through the microprocessor; the support comprising a rotary joint and a fixed base, the rotary joint allowing the clamped main body component to be adjusted in an angle range of 0-180 DEG, the rotary joint being rotationally connected with the fixed base through an extension rod; the rotary joint being provided with a support part for placing the main body component. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ； calculating the roughness Ra of the inner wall of the hole; wherein k is a calibration factor; is a correction factor based on the laser diode power P; is the standard deviation of the optical fiber intensity; is the initial reference standard deviation; P is the actual laser power; P0 is the reference power baseline.

2. The device for detecting the smoothness of the inner wall of the hole of the solid wood furniture according to claim 1, characterized in that, ​ ​ 3. The device for detecting the smoothness of the inner wall of the hole of the solid wood furniture according to claim 2, characterized in that, ​ ​ 4. The device for detecting the smoothness of the inner wall of the hole of the solid wood furniture according to claim 3, characterized in that, ​ ​ ​ ​ ​ 5. The device for detecting the smoothness of the inner wall of the hole of the solid wood furniture according to claim 1, characterized in that, ​ ​ 6. The device for detecting the smoothness of the inner wall of the hole of the solid wood furniture according to claim 1, characterized in that, ​ 7. The device for detecting the smoothness of the inner wall of the hole of the solid wood furniture according to claim 6, characterized in that, ​

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