A special hole inner diameter measuring instrument

Abstract

The present application aims at the problem that the measurement result is inaccurate due to the influence of oil stain, water stain or reflection on the measuring surface when the aperture is measured by the laser measuring instrument in the prior art, and provides a special-shaped aperture measuring mechanism, which comprises three measuring devices, each of which comprises a measuring rod, a measuring rod driving device and a measuring rod guiding device, the measuring rods are arranged in parallel, the measuring rod driving device drives the measuring rods to reciprocate under the action of the guiding device, so that the three measuring rods approach or move away from each other, a light-transmitting hole is arranged on each measuring rod along the length direction of the measuring rod, and a measuring structure is arranged on the outer surface of the measuring rod at a measuring working position, the structure of the present application combines the mechanical and visual, the measuring rod contacts the inner hole wall of the workpiece, is not affected by the reflected light, oil stain and water stain, and the relatively real and reliable measurement data can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to a measuring instrument, in particular to an instrument for measuring an inner hole. BACKGROUND

[0002] In the inner hole size measurement of a hole, a special measuring tool such as a vernier caliper is usually used, but the measuring tool itself has low measurement accuracy, and the actual operation is performed by a person, so the randomness is strong, and the accuracy of the measurement is poor. For this reason, the inner hole measuring instrument is developed in the art, and the inner hole with high precision requirement is measured, such as the Chinese invention patent with the patent number 201710757290.8, which provides a three-point hole inner diameter measuring instrument, including a scale frame, a scale body and a measuring rod, the scale body is slidably arranged in the scale frame, three measuring rods with the same length are circumferentially arranged at the front end of the scale frame, the inner ends of the measuring rods are hingedly connected to the scale frame, the scale body is connected to the scale frame through a closing and opening mechanism, the closing and opening mechanism closes the measuring rods to the smallest hole diameter measurement position corresponding to the maximum extension of the measuring rods at the front end of the scale frame, the closing and opening mechanism opens the measuring rods to the largest hole diameter measurement position corresponding to the minimum extension of the measuring rods at the front end of the scale frame, the scale frame is provided with a digital display device for converting the retraction amount of the scale body into the size of the hole diameter measured by the measuring rod, and the measured structure is displayed through the digital display device. By using the above structure, when measuring a large and regular surface inner hole, the accuracy of the measurement can be achieved, but when measuring the inner diameter of a small hole or a special-shaped hole, since the measuring rod is consistent with the direction of the hole diameter, it cannot be inserted into the hole, and needs to be inserted obliquely, which will affect the measurement accuracy and make the measurement inaccurate. For this reason, the industry has designed and researched the measuring instrument using a laser sensor for measurement, but since the inner surface of the special-shaped hole is irregular, the diameters of the holes are different in the axial direction, and have chamfers and other special-shaped surfaces, when the light hits the chamfer or the interface between two different hole diameters during the machining process, the light will be reflected, and during the machining process of the hole, oil stains, water and other oil films or water films will be formed, or small particles will be attached, when the light meets these pollutants, scattering will occur, which will make the measurement result inaccurate, therefore, the accurate measurement of the inner diameter of the special-shaped hole, especially the small-diameter special-shaped hole, such as the special-shaped hole of the wheel hub of an automobile or a motorcycle, has become a new problem in the industry. SUMMARY

[0003] The purpose of the present application is to provide a special-shaped hole diameter measuring mechanism to solve the problem of inaccurate measurement result caused by light reflection due to the influence of oil stains, water stains or reflection on the measuring surface when using a laser measuring instrument to measure the hole diameter in the prior art.

[0004] The purpose of the present application is achieved by the following technical scheme:

[0005] An irregular hole inner diameter measuring instrument, comprising a vision device (100), a measuring device (200), and a frame body (300), the measuring device comprises three measuring devices, each measuring device comprises a measuring rod, a measuring rod driving device, and a measuring rod guiding device, the measuring rods are arranged in parallel, the measuring rod driving device drives the measuring rods to reciprocate under the action of the guiding device, so that the three measuring rods approach or move away from each other, a light transmission hole is arranged on each measuring rod along the length direction of the measuring rod, and a measuring structure is arranged on the outer surface of the measuring rod at a measuring working position; the frame body comprises a bottom plate, the three measuring devices are arranged on the bottom plate, a through hole is arranged on the bottom plate, and the three measuring rods are located in and pass through the through hole; the vision device comprises a lens, the lens is located above the bottom plate, the movable area of the light transmission hole of the three measuring rods is located in the range of the lens, the light spot position image of the light transmitted through the light transmission hole is obtained by shooting the light transmitted through the light transmission hole by the lens, and the vision device further comprises a control device, an output end of the vision device is connected with an input end of the control device, the control device comprises a graphic processing calculation module, the graphic processing calculation module fits the inner diameter value of the measured hole according to the obtained light transmission hole position image and displays the inner diameter value;

[0006] A qualified comparison judgment module is arranged in the control device, the hole diameter size calculated by measurement is compared with the standard size stored in the memory, and whether it is qualified is judged;

[0007] The measuring structure is a long rectangular plane or a circular dot, and the length direction of the long rectangular plane extends along the length direction of the measuring rod;

[0008] The measuring rod driving device is a gas cylinder, and the guiding device comprises a high-precision guide rail one and a high-precision sliding groove one, and the guide rail one and the sliding groove one are connected in sliding fit;

[0009] Further comprising a lifting device (400), the frame body further comprises a vertical frame, the lens is supported by a lens holder, the lifting device comprises a lifting driving device and a lifting sliding table, the lifting sliding table is connected with the vertical frame in sliding mode, the lens is fixedly connected with the lifting sliding table through the lens holder, and the lifting sliding table is driven by the lifting driving device to reciprocate along the extension direction of the light transmission hole;

[0010] The lifting driving device is a gas cylinder or a servo cylinder, when the irregular hole inner diameter measuring instrument comprises the control device, the lifting driving device is electrically connected with the output port of the control device, the control device comprises a distance calculation module, the control device drives the lifting driving device to act according to the calculated distance from the measuring rod, so as to adjust the distance between the lens and the measuring rod;

[0011] The control device is a PLC;

[0012] At least the measuring structure part of the measuring rod is made of wear-resistant material or is provided with a wear-resistant layer;

[0013] The collected image is analyzed and processed by an image acquisition analysis processing module, the image acquisition analysis processing module selects the position of the light spot 1 formed by the light transmission of the light transmission hole (204) through the viewfinder window (2), the diameter of the viewfinder window is larger than the diameter of the light transmission hole, a ring-shaped area (4) is formed between the light spot and the viewfinder window, the edge pixel points of the light spot are automatically screened in the ring-shaped area according to the software setting, a curve is formed and fitted into a circle, the center point of the circle is taken as the center position of the light transmission hole, the center O of the measured special-shaped hole is determined according to the center positions of the three fitted light transmission holes, and the radius R of the measured special-shaped hole is calculated, so that the diameter of the special-shaped hole is measured. The special-shaped hole diameter measuring instrument adopting the structure of the present application is combined with the mechanical and visual structures, the measuring rod is in contact with the inner hole wall of the workpiece, is not affected by reflected light, oil stains and water stains, the contact between the measuring rod and the measured hole diameter is stable and reliable, the position of the hole wall is collected by the visual device, therefore, the measurement data is relatively true and reliable; the overall system adopts a cylinder or an electric cylinder as the tensioning power, is provided with a pressure gauge to control the tension size, adopts a high-precision guide rail as the guide to ensure the rigidity and stability of the mechanical structure, the displacement of the measuring rod is obtained by the visual device, the visual device is reliably fixed, is not swung during measurement, and only the focal length is adjusted according to the size of the workpiece, therefore, the overall system has high measurement precision, the measurement result is stable and reliable. The measuring instrument of the present application skillfully uses the respective advantages of the visual device and the mechanical device, the stability of the mechanical measurement can be obtained, and the high precision of the visual measurement can also be obtained. The present measuring instrument is particularly suitable for the measurement of the special-shaped hole diameter with a regular radial cross section and a relatively long axial direction. BRIEF DESCRIPTION OF DRAWINGS

[0014] Fig. 1 It is a structural schematic diagram of an embodiment of the special-shaped hole inner diameter measuring instrument of the present application.

[0015] Fig. 2 It is a structural schematic diagram of an embodiment of the special-shaped hole inner diameter measuring instrument of the present application.

[0016] Fig. 3 It is a principle diagram of three light transmission spots fitted into a circle.

[0017] BRIEF DESCRIPTION OF DRAWINGS

[0018] 100-visual device

[0019] 101-lens

[0020] 200-measuring device

[0021] 201-driver, 202-piston rod, 203-bracket, 204-light transmission hole, 205-measuring rod, 206-slide plate one, 207-guide rail one, 208-rectangular long strip plane

[0022] 300-frame body

[0023] 301 - Vertical stand; 302 - Base plate; 303 - Through hole; 304 - Lens holder

[0024] 400 - Lifting device; 401 - Lifting slide; 402 - Lifting drive device;

[0025] 1-Light spot 2-Viewfinder 3-Field of view Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments:

[0027] like Figs. 1 to 3 As shown, the present invention provides an instrument for measuring the inner diameter of irregular holes. The device includes a vision device 100, a measuring device 200, a frame 300, and a lifting device 400. The frame supports and fixes the measuring device, the vision device, and the lifting device. The frame 300 includes a vertical frame 301 and a base plate 302. The base plate supports and fixes the measuring device, the vertical frame supports the lifting device, and the lifting device raises and lowers the lens of the vision device.

[0028] The three sets of measuring devices each include a measuring rod 205 and a measuring drive device for driving the measuring rod to advance and retreat, the measuring drive device including a driver 201, a guide device I including a slide plate I 206 and a guide rail I 207, the slide plate I 206 being fixedly connected with the output end of the driver, the front end of the slide plate I being connected with the measuring rod 205, at least the rear end of the lower surface being provided with a sliding groove I, the sliding groove I being connected with the guide rail I, the guide rail I being arranged on the base plate, the length direction of the guide rail I being arranged in the same direction as the advancing and retreating direction of the measuring rod; the length direction of the measuring rod being perpendicular to the advancing and retreating direction of the measuring rod, the driver driving the slide plate to advance or retreat so as to drive the measuring rod to advance or retreat. A cylinder is usually used as the driver, the piston rod 202 of the cylinder is connected with the slide plate I through a support 203, the length direction of the piston rod is arranged in the same direction as the length direction of the guide rail I. High-precision guide rail I and sliding groove I are preferably used, of course, a sliding block can also be arranged on the lower surface of the slide plate I as the guide rail I, a guide rail groove is arranged on the base plate as the sliding groove I, the frame body 300 includes a base plate 302 and a vertical frame 301, a through hole 303 is arranged on the base plate, the base plate is usually arranged horizontally, the driver is fixedly arranged on the base plate, the measuring rod is arranged in the through hole 303 arranged on the base plate, the length direction of the measuring rod is parallel to the hole center line of the through hole 303, a light transmission hole 204 is arranged on the measuring rod along the length direction of the measuring rod, the light transmission holes of the measuring devices are uniformly distributed around the through hole, and the distance between the hole center lines of the light transmission holes of the measuring devices and the hole center line of the through hole is equal, that is, the hole center lines of the light transmission holes are arranged on a circle, and the hole center line of the through hole is arranged on the same line. When the measuring driver is a cylinder, the cylinder body is fixedly arranged on the base plate, the head of the piston rod of the cylinder is fixedly connected with the upper surface of the slide plate I through the support 203, the lower surface of the slide plate I is provided with the sliding groove I, and the measuring rod is arranged on the lower surface of the slide plate I. At least the surface of the outer surface of the measuring rod facing the wall of the measured hole is provided with a measuring surface, the measuring surface can be a point surface or a long strip-shaped plane, and the measuring surface is preferably a rectangular long strip-shaped plane. The rectangular long strip-shaped plane is arranged on the measuring rod as the measuring surface for contacting the inner hole of the measured workpiece. Since the rectangular long strip-shaped plane contacts the measured surface through at least two lines, the measuring result is more reliable. The distance between the measuring surface of each measuring device and the center line of the light transmission hole is equal. In this way, the displacement amount of the measuring surface can be calculated by obtaining the displacement amount of the light transmission hole, so as to obtain the diameter of the measured inner hole.

[0029] The lifting device 400 includes a lifting drive device 402 and a lifting sliding table 401, the lifting drive device being connected with the lifting sliding table, the lifting sliding table 401 being slidingly connected with the vertical frame, the sliding direction of the lifting sliding table being in the same direction as the extending direction of the measuring hole, the camera lens 101 being fixedly connected with the lifting sliding table 401 through a lens holder 304, the lifting sliding table being driven by the lifting drive device to move towards the base plate or away from the base plate, so as to drive the camera to move towards the base plate or away from the base plate for focal length adjustment. The activity range of the light transmission hole on the measuring rod of each measuring device is located within the viewfinder range of the lens of the camera, and the camera can focus on the light transmission hole.

[0030] In use, the workpiece to be measured (not shown in the figure) is located below the base plate, a light source (not shown in the figure) is arranged below the base plate, and the workpiece to be measured is fixed by the clamping device, and the center line of the hole of the workpiece to be measured is arranged in line with the axis of the cylinder in which the center line of each light-transmitting hole is located or in line with the center line of the through hole. The measuring rods of each measuring device are close together and located in the measuring holes. The measuring rods are pulled out, that is, retreated, by the driver, and the measuring rods remain stationary when the driver cannot pull the measuring rods. The camera takes a picture to obtain the positions of the measuring holes and thus calculate the inner hole of the workpiece to be measured.

[0031] As a preferred scheme, a pressure gauge is arranged on the gas supply line of the air cylinder to detect the pulling force on the air cylinder, so that the pulling force of the air cylinder on the measuring rod is moderate, and the workpiece to be measured is not deformed due to the pulling force of the air cylinder.

[0032] The working surface of the measuring rod is a wear-resistant surface to form a three-point wear-resistant measuring head. The measuring rod or the measuring structure itself can be made of wear-resistant material, or a wear-resistant layer can be arranged on the working surface thereof.

[0033] The measuring instrument of the present application is used in combination with a control device such as a PLC, the lifting driving device is connected to the output port of the control device, and the vision device is connected to the input port of the control device. An image processing module and a calculation module are arranged in the control device or the vision device to process and calculate the positions of the light-transmitting holes obtained by the camera and fit the hole diameter of the measuring hole. In a better scheme, a qualified comparison judgment module is arranged to compare the hole diameter calculated by the measurement with the standard size stored in the memory to determine whether it is qualified.

[0034] The lifting driving device 402 preferably adopts an air cylinder or a servo cylinder, so that the camera can be accurately positioned to the required position. The lifting driving device is preferably electrically connected to the output port of the control device, and the control device is provided with a distance measurement module. The control device drives the lifting driving device to act according to the measured distance from the measuring rod, so as to adjust the distance between the lens and the measuring rod.

[0035] In use, the hub is conveyed to the measuring station by a flow line or manually and is accurately positioned, so that the workpiece to be measured is located below the through hole 303.

[0036] 2) The camera lens is lowered to the measuring height by the servo cylinder, and the three air cylinders pull the corresponding measuring rods to move to press the inner wall of the measured hole. It should be noted that the installation position of the camera should be such that the measuring rod is within the field of view 3 thereof.

[0037] 3) The camera takes a picture to feed back the obtained data to the control device PLC.

[0038] 4) The program in the PLC automatically runs calculation, measures the aperture size, and compares with the standard size to determine whether the workpiece is qualified.

[0039] The image acquisition and analysis processing module is used to analyze and process the collected images. Preferably, the image acquisition and analysis processing module selects the position of the light spot 1 formed by the light transmission hole 204 through the viewfinder window 2. The diameter of the viewfinder window is larger than that of the light transmission hole. An annular region 4 is formed between the light spot and the viewfinder window. The edge pixels of the light spot in the annular region are automatically selected according to the software settings, a curve is formed and fitted into a circle, the center point of the circle is taken as the center position of the light transmission hole, the center O of the measured special-shaped hole is determined according to the center positions of the three fitted light transmission holes, and the radius R of the measured special-shaped hole is calculated, so as to measure the diameter of the special-shaped hole. The above-mentioned image acquisition and processing module is used to process the collected light transmission, which can effectively remove the interference of other light points when taking pictures, remove the light points formed by stray light, reduce the position error of the obtained light transmission hole, and ensure the measurement accuracy. When the annular region is interrupted or there are other stray points due to environmental factors, the complete circle can be fitted according to the most part of the light spot edge curve, so as to determine the center position of the light transmission hole. Therefore, through the image processing technology, the adaptability of the device to the environment is better, the interference from the external environment is small, and the measurement accuracy is higher.

Claims

1. A profile hole inner diameter measuring instrument, characterized by, The application relates to a visual device (100), a measuring device (200) and a frame body (300), wherein the measuring device comprises three measuring rods, a measuring rod driving device and a measuring rod guiding device, the measuring rods are arranged in parallel, the measuring rod driving device drives the measuring rods to reciprocate under the action of the guiding device, the three measuring rods are close to or far away from each other, a light transmission hole is arranged on each measuring rod along the length direction of the measuring rod, and a measuring structure is arranged on the outer surface of the measuring rod at a measuring working position; the frame body comprises a bottom plate, the three measuring devices are arranged on the bottom plate, a through hole is arranged on the bottom plate, and the three measuring rods are located in and pass through the through hole; the visual device comprises a lens, the lens is located above the bottom plate, the activity area of the light transmission hole of the three measuring rods is located in the viewfinder range of the lens, the light spot position image of the light transmitted through the light transmission hole is obtained by shooting the light transmitted through the light transmission hole by the lens, a control device is further arranged, the output end of the visual device is connected with the input end of the control device, the control device comprises a graphic processing calculation module, the graphic processing calculation module fits the inner diameter value of the measured hole according to the obtained light transmission hole position image and displays the value, and a qualified comparison judging module is arranged in the control device to compare the hole diameter size calculated by the measurement with the standard size stored in the memory and judge whether the hole diameter size is qualified.

2. A profile hole inside diameter measuring instrument as claimed in claim 1, wherein, The measuring structure is a long strip rectangular plane or a dot, and the length direction of the long strip rectangular plane extends along the length direction of the measuring rod.

3. A profile hole inside diameter measuring instrument as claimed in claim 1, wherein, The measuring rod driving device is a cylinder, and the guiding device comprises a high-precision guide rail I and a high-precision sliding groove I.

4. A profile hole inside diameter measuring instrument as claimed in claim 1 or 2, characterized in that The application further relates to a lifting device (400), and the frame body further comprises a vertical frame, the lens is supported by a lens holder, the lifting device comprises a lifting driving device and a lifting sliding table, the lifting sliding table is slidably connected with the vertical frame, the lens is fixedly connected with the lifting sliding table through the lens holder, and the lifting sliding table is driven by the lifting driving device to reciprocate along the extension direction of the light transmission hole.

5. A profile hole inside diameter measuring instrument as claimed in claim 4, wherein, The lifting driving device is a cylinder or a servo cylinder, when the control device is arranged, the lifting driving device is electrically connected with the output port of the control device, the control device comprises a distance calculation module, the control device drives the lifting driving device to act according to the calculated distance from the measuring rod, so as to adjust the distance between the lens and the measuring rod.

6. A profile hole inside diameter measuring instrument as claimed in claim 1, wherein, The control device is a PLC.

7. A profile hole inside diameter measuring instrument as claimed in claim 1, wherein, At least the measuring structure part of the measuring rod is made of wear-resistant material or is provided with a wear-resistant layer.

8. The profile hole bore gauge of claim 1 wherein, The collected image is analyzed and processed by an image acquisition analysis processing module, the image acquisition analysis processing module selects the position of the light spot 1 formed by the light transmission of the light transmission hole (204) through a viewfinder window (2), the diameter of the viewfinder window is larger than that of the light transmission hole, a ring-shaped area (4) is formed between the light spot and the viewfinder window, the edge pixel points of the light spot are automatically selected in the ring-shaped area according to software setting, a curve is formed and fitted into a circle, the center point of the circle is taken as the center position of the light transmission hole, the center O of the measured special-shaped hole is determined according to the center positions of the three fitted light transmission holes, and the radius R of the measured special-shaped hole is calculated, so that the diameter of the special-shaped hole is measured.

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