Inner diameter measuring device and system thereof

Abstract

The invention provides an inner diameter measuring device which can obtain an accurate measurement result even in an environment where large electromagnetic noise is generated in a state that the inner diameter measuring device is installed on a mechanical arm. An inner diameter measuring device for measuring the inner diameter of a hole formed in a workpiece, the inner diameter measuring device being removably attached to the tip of a robot arm (14), the inner diameter measuring device comprising: at least two measuring elements (270) that abut against the inner wall surface of the hole formed in the workpiece, the at least two measuring elements (270) being configured so that the at least two measuring elements (270) are in contact with the inner wall surface of the hole formed in the workpiece, and the at least two measuring elements (270) being in contact with the inner wall surface of the hole formed in the workpiece; the data converting and transmitting part converts analog data related to the displacement of the at least two measuring pieces into digital data representing the inner diameter of the hole and then transmits the digital data to external equipment.

Description

Technical Field

[0001] The present disclosure relates to an inner diameter measuring device and a system thereof. The inner diameter measuring device is detachably mounted on a top end portion of a robot arm and is used to measure the inner diameter of a hole formed in a workpiece. Background Art

[0002] Automotive parts and other workpieces are produced using six-axis industrial robots and collaborative robots. These robots enable more labor-efficient mass production. These workpieces require accurate measurement at every stage of manufacturing. Therefore, efforts are underway to automate these measurements using industrial robots.

[0003] When measuring the inner diameter of a workpiece, a method can be used in which the measuring unit of an inner diameter measuring device, mounted on the tip of an arm (also known as a manipulator) such as an industrial robot, is inserted into the object for measurement. In this case, if the outer diameter of the measuring unit is slightly smaller than the inner diameter of the workpiece, high-precision measurement is easily achieved.

[0004] The typical measurement procedure is as follows. First, a small gap is created between the workpiece and the measuring unit, and the measuring unit is inserted into the workpiece while maintaining this gap. Next, if the inner diameter measuring device is, for example, a pneumatic micrometer, measurement is performed while maintaining a small distance between the measuring unit and the inner wall of the workpiece. If the inner diameter measuring device is a contact type, measurement is performed by pressing a contactor against the inner wall of the workpiece at the measuring position. Patent Documents 1 to 3 describe examples of such workpiece inner diameter measuring devices.

[0005] Patent Documents 4 and 5 disclose methods in which an inner diameter measuring device having a contact-type stylus head is mounted on the top end of a robot arm to measure the inner diameter of a workpiece.

[0006] Patent Document 1: Japanese Patent No. 6910668 Patent Document 2: Japanese Patent Application Laid-Open No. 10-339623 Patent Document 3: Japanese Patent No. 7238187 Patent Document 4: Japanese Patent Application Laid-Open No. 2023-142301 Patent Document 5: Japanese Patent Application Laid-Open No. 2023-142303 Patent Document 6: Japanese Patent Application Laid-Open No. 2018-169180 Summary of the Invention -Technical problem to be solved by the invention-

[0007] Pneumatic micrometers are mostly used to measure the aperture of workpieces. This is because pneumatic micrometers have advantages such as being able to utilize air sources that are generally supplied in larger quantities in factories. When using a pneumatic micrometer to measure the aperture (inner diameter of the workpiece), the blowing reaction force of the air is measured. Therefore, it is preferred to maintain a small distance between the air outlet and the inner wall of the workpiece. For example, the gap between the air outlet and the inner wall of the workpiece can be set to less than 0.5 mm, specifically, it can be set to about 0.1 mm. In addition, the gap with the wall portion other than the air outlet is smaller, sometimes also set at 0.01 to 0.1 mm. It should be noted that the air outlet is sometimes referred to as a "nozzle" and the wall portion other than the air outlet is sometimes referred to as a "guide portion."

[0008] As mentioned above, the distance between the measuring unit and the inner wall of the workpiece is very small, and inserting the measuring unit into the workpiece requires precise positioning, etc. In particular, when using a robot for automatic measurement, it is necessary to detect the workpiece, accurately position the workpiece, and position the pneumatic micrometer relative to the workpiece. In addition, the robot needs to be taught the operating movements of the pneumatic micrometer. If the hole diameters of a large number of workpieces (mass-produced) are to be measured sequentially, not only may the position of the hole deviate, but the robot's stop position (the starting position of the measurement movement) may also deviate each time. Therefore, the operation of inserting the measuring unit into the workpiece (hole) itself is very difficult. In addition, if forced insertion is attempted, the "seizure" phenomenon described later may occur, resulting in damage to the workpiece and / or the measuring unit.

[0009] Patent Document 1 discloses a method for using a floating mechanism to align the center of the hole being measured with the center of the measuring part of a pneumatic micrometer. This allows for high-precision and rapid measurements even if the positioning of the robotic arm is insufficient. However, the method described in Patent Document 1 has the following problems: because the workpiece is only allowed to move in the horizontal direction, the hole is limited to the upward direction, making it impossible to perform general hole measurement. In addition, because a pneumatic micrometer is used, a separate external part is required to convert the pressure and flow of the air into measured values, which requires space and piping, making it relatively cumbersome.

[0010] When using a pneumatic micrometer, there's only a tiny gap between the outer diameter of the measuring unit and the inner wall of the hole being measured. Therefore, when mechanically inserting the measuring unit into the hole, special measures are required to prevent collision or "seizure" between them. Patent Document 2 doesn't describe such measures.

[0011] Another approach to addressing this issue involves teaching the robot the position of the hole being measured and then using force sensors for feedback control to account for individual workpiece variations. In this case, feedback control is typically performed in conjunction with a PLC. However, the control programs for teaching and / or coordinating these controls are often complex, and force sensors are often expensive.

[0012] Patent Document 3 discloses a method for measuring the inner diameter of a workpiece's hole by placing multiple measuring tools (contact elements) in contact with the inner wall of the hole being measured. The measuring tools are configured to retract into the interior of the measuring unit. In this method, the multiple measuring tools retract into the measuring unit when inserted into the hole being measured.

[0013] Implementing this solution using an inner diameter measuring device mounted on a robotic arm presents other challenges. Generally speaking, robotic arms have multiple degrees of freedom, sometimes up to six. Repeatedly positioning such a robotic arm to the same hole position is difficult. Continuous measurement of mass-produced products also requires speed, but the method of Patent Document 3 presupposes multiple measurements. For these reasons, the method of Patent Document 3 is unsuitable for implementation using a robotic arm.

[0014] Patent Documents 4 and 5 disclose methods for measuring the inner diameter of a workpiece by attaching an internal diameter measurement unit with a contact-type stylus head to the tip of a robotic arm. The measurement units described in these documents include a collision detector and a force sensor, which retract the workpiece during insertion. This protects the workpiece even if the stylus head collides with the workpiece during insertion.

[0015] However, because the measurement unit is mounted on the robot arm, it introduces a new problem: electromagnetic noise. Industrial robots often use servo motors and other control systems to control their movements. In this case, the electromagnetic noise generated by the motors and control units is generally high. A major factor is that the servo motors repeatedly make fine adjustments to their position even when they appear to be stationary. This high electromagnetic noise can adversely affect the minute detection signals from the measurement unit.

[0016] The present disclosure aims to solve at least one problem existing in the prior art. One specific problem is to provide an inner diameter measuring device that, when mounted on a robotic arm, can obtain accurate measurement results even in an environment generating significant electromagnetic noise. Another specific problem is to provide an inner diameter measuring system that can automatically insert a measuring portion into the measured holes of a large number of workpieces without damaging the measuring portion. Another specific problem is to provide an inner diameter measuring system that can automatically measure the measured holes of workpieces having different diameters (different nominal diameters). -Technical solutions to solve technical problems-

[0017] One embodiment of the inner diameter measuring device disclosed herein is an inner diameter measuring device, which is detachably mounted on the top end of a robotic arm and is used to measure the inner diameter of a hole formed on a workpiece. The inner diameter measuring device includes at least two measuring parts and a data conversion and sending part. The at least two measuring parts abut against the inner wall surface of the hole formed on the workpiece. The data conversion and sending part converts analog data related to the displacement of the at least two measuring parts into digital data representing the inner diameter of the hole and sends it to an external device. -Effects of the Invention-

[0018] According to the present disclosure, at least one problem existing in the prior art can be solved. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of an embodiment of an inner diameter measuring system. Figure 2 It is a perspective view of an embodiment of an inner diameter measuring device. Figure 3 yes Figure 2 A longitudinal sectional view of the main parts of the inner diameter measuring device shown. Figure 4 It is a perspective view of the main parts of another embodiment of the inner diameter measuring device. Figure 5 yes Figure 4 An explanatory diagram of a tilt compensation method for an inner diameter measuring device shown. DETAILED DESCRIPTION

[0019] The first embodiment of the inner diameter measuring device disclosed herein is an inner diameter measuring device, which is detachably mounted on the top end of a robotic arm and is used to measure the inner diameter of a hole formed on a workpiece. The inner diameter measuring device includes at least two measuring parts and a data conversion and sending part. The at least two measuring parts abut against the inner wall surface of the hole formed on the workpiece. The data conversion and sending part converts analog data related to the displacement of the at least two measuring parts into digital data representing the inner diameter of the hole and sends it to an external device.

[0020] A characteristic of the aforementioned inner diameter measuring device is that it includes a data conversion and transmission unit. This unit is integrated with the inner diameter measuring device. The inner diameter measuring device is removably mounted on the top of the robotic arm. In other words, the inner diameter measuring device is replaceable. The inner diameter measuring device also includes a data conversion and transmission unit that converts analog data into digital data.

[0021] The data conversion and transmission unit converts analog data into digital data representing the inner diameter of the hole being measured. This analog data is raw measurement data related to the displacement of the measuring piece. The data conversion and transmission unit then transmits this digital data to an external device. For example, the external device may be a computer, such as a control device for a robotic arm (robot).

[0022] As mentioned above, there is often considerable electromagnetic noise around the robotic arm. If this electromagnetic noise is mixed into the data representing the inner diameter of the hole, it could affect the stability and accuracy of the measurement. However, the inner diameter measuring device described above utilizes an integral data conversion and transmission unit to transmit the measured data as digital data to the outside world. Even in environments with considerable electromagnetic noise, it is easy to accurately transmit and receive digital data. Therefore, when the inner diameter measuring device described above is applied to automated inner diameter measurement using a robotic arm, it can achieve both stable measurements and highly accurate measurement data.

[0023] A second embodiment of the inner diameter measuring device disclosed herein is the inner diameter measuring device according to the first embodiment, wherein the data conversion and transmission section transmits the digital data to the external device connected by wire.

[0024] Preferably, the data conversion and transmission unit transmits the digital data to an external device (eg, a control device for a robot arm) via a wired connection. In this case, the data conversion and transmission unit may also receive power from the external device via the same wired connection.

[0025] The third embodiment of the inner diameter measuring device disclosed herein is an inner diameter measuring device, which, based on the first embodiment, includes a plug gauge and a connecting portion, wherein the plug gauge holds the at least two measuring pieces at the top end, and the connecting portion is arranged between the plug gauge and the data conversion and sending portion, and the connecting portion is configured to allow the robotic arm to displace in the axial direction and in a direction substantially perpendicular to the axial direction relative to the plug gauge.

[0026] A characteristic feature of the aforementioned inner diameter measuring device is its inclusion of a connecting portion. This connecting portion is configured to allow displacement of the robotic arm in both the axial direction and a direction substantially perpendicular thereto. When performing inner diameter measurement using the robotic arm, the inner diameter measuring device is inserted into the hole of the workpiece being measured. The inclusion of the connecting portion significantly reduces any damage caused by accidental contact between the workpiece and the inner diameter measuring device during insertion, due to, for example, misalignment of the workpiece. This damage includes malfunction of the gauge and / or damage to the workpiece.

[0027] Furthermore, by utilizing the connection to allow the robot arm to move in a direction roughly perpendicular to the axial direction, the time required for teaching can be further reduced. Teaching is performed on the robot arm. Through teaching, the insertion position (hole position) is pre-stored. Even if the hole being measured deviates from this position, the connection can absorb this deviation. Therefore, even with low teaching accuracy, the inner diameter measuring device can be smoothly inserted into the hole.

[0028] The fourth embodiment of the inner diameter measuring device disclosed in the present invention is an inner diameter measuring device, which is based on the third embodiment, and the connecting part is formed into a vertically long cylindrical shape as a whole. The connecting part includes a bushing seat formed in a circular ring shape, a floating mechanism, a yielding mechanism and a measuring mechanism respectively retained in the bushing seat, the floating mechanism allows the displacement in a direction approximately perpendicular to the axial direction, the yielding mechanism allows the displacement in the axial direction, the measuring mechanism obtains the analog data, and the measuring mechanism is arranged in the center part of the bushing seat, and the floating mechanism and the yielding mechanism are arranged around it.

[0029] In the case of internal diameter measuring devices with floating mechanisms and yielding mechanisms, which are commonly arranged in series with the measuring mechanism, the above-mentioned internal diameter measuring device is more compact (shorter in length), thereby reducing the torque applied to the robot arm.

[0030] Incorporating a data transmission converter into an inner diameter measuring device introduces a new problem: the device becomes slightly heavier and larger. However, the aforementioned inner diameter measuring device solves this problem by incorporating a connecting portion that performs three functions, shortening the overall length. These three functions are a floating mechanism, a yielding mechanism, and a measuring mechanism. The floating and yielding mechanisms facilitate and smooth insertion of the inner diameter measuring device into the hole.

[0031] The fifth embodiment of the inner diameter measuring device disclosed herein is an inner diameter measuring device. Based on the fourth embodiment, the yielding mechanism includes at least three ball bushings and a bushing shaft. The at least three ball bushings are arranged with spacing along the circumference of the bushing seat. The bushing shaft is arranged relative to each of the ball bushings and passes through the center of the ball bushing.

[0032] A sixth embodiment of the inside diameter measuring device disclosed herein is the inside diameter measuring device according to claim 4 , wherein, in addition to the fourth embodiment, the floating mechanism includes an elastic body, and one end of the elastic body is locked to the bushing seat.

[0033] The seventh embodiment of the inner diameter measuring device disclosed herein is an inner diameter measuring device, which is based on the first embodiment, wherein the at least two measuring parts are four measuring parts, and the inner diameter measuring device includes displacement measuring devices respectively connected to the four measuring parts, and the four measuring parts are arranged with spacing along the circumferential direction. The data conversion and sending part converts the analog data detected by the displacement measuring device into digital data representing the inner diameter of the hole and sends it to the external device.

[0034] According to the above-mentioned inner diameter measuring device, more accurate inner diameter measurement can be performed. Because it includes four measuring parts, it is particularly useful for situations where the axis of the inner diameter measuring device is not parallel to the axis of the hole (tilted situation). Based on the displacement of the four measuring parts, the slope θ of the inner diameter measuring device can be calculated more accurately. The positions of the four measuring parts are not particularly limited. Preferably, the two groups of measuring parts are arranged at opposite positions in the circumferential direction of the inner diameter measuring device (180 degrees apart). There is no special limitation on the arrangement of the two groups of measuring parts. Preferably, the four measuring parts are arranged 90 degrees apart in the circumferential direction.

[0035] A first embodiment of the inner diameter measuring system disclosed herein is an inner diameter measuring system, comprising the robot arm and the inner diameter measuring device described in any one of the first to seventh embodiments.

[0036] The above-described inner diameter measurement system, through the structure and functions of the inner diameter measuring device, is capable of both stable measurement and highly accurate data. The following illustrates an embodiment of the inner diameter measuring device and the inner diameter measurement system incorporating the same, using accompanying drawings. For mass-produced products such as automotive parts and household appliances, it is sometimes necessary to measure the inner diameters of holes in workpieces of varying diameters (different types, different nominal diameters). To reduce manufacturing cycle time, using a robot allows for unmanned and highly efficient measurement.

[0037] Figure 1 1 is a perspective view of an embodiment of an inner diameter measuring system 50 including an inner diameter measuring device 100. The inner diameter measuring system 50 uses a robot 10 to perform unmanned measurement of a hole in a workpiece. The inner diameter measuring system 50 includes a conveyor 140, the robot 10, and a tool table 130.

[0038] The conveyor 140 continuously carries in the workpieces 150 that have been processed by drilling, etc. It should be noted that the inner diameter measuring system 50 may also include a measuring table instead of the conveyor 140 .

[0039] A plurality of holes 152 and 154 having different diameters are formed in a workpiece 150 , which is an object to be measured. The workpiece 150 waits on a conveyor 140 for each hole 152 and 154 to be measured.

[0040] The inner diameter measuring system 50 also includes a tool table 130. A plurality of tool holders 122 are fixed to the tool table 130. Each tool holder 122 holds an inner diameter measuring device 100, 100, ..., having a different outer diameter (nominal diameter). One inner diameter measuring device 100 is currently in use.

[0041] The inner diameter measuring device 100 in use is removed from the tool holder 122 at the right end of the tool table 130. Multiple inner diameter measuring devices 100, 100, etc. can be interchangeably mounted on the top end of the robot arm 14. This allows measurement of holes 152, 154 of different inner diameters formed in a workpiece 150.

[0042] An automatic robot 10 is provided between the tool table 130 and the conveyor 140. The automatic robot 10 is a multi-joint multi-degree-of-freedom robot that can operate in an unmanned state.

[0043] Mounted on the top of the robotic arm 14 is an internal diameter measuring device 100, held by a tool holder 122. The robot 10 is connected to a robot controller 12 via wiring 16 (wired connection). The robot 10's movements are pre-programmed, and all measurement-related actions are performed automatically or unmanned. It should be noted that the robot controller 12 is typically a computer comprising a processor and memory. The computer, or robot controller 12, loads programs stored in the memory, which are executed by the processor, thereby controlling various components of the internal diameter measurement system.

[0044] The robot 10 moves the top end of the robot arm 14 to any position and angle by rotating each joint. To do this, first, the robot arm 14 is brought close to the upper surface of the inner diameter measuring device 100 held by the tool holder 122. Then, the top end of the robot arm 14 is translated from the top (opening) side of the guide portion 124 of the tool holder 122. The tool-side changer 128 and the robot-side changer 126 are then engaged and fixed to integrate the inner diameter measuring device 100 with the robot arm 14. The state in which the robot-side changer 126 and the tool-side changer 128 are integrated is called a robot changer.

[0045] The method for separating the hand changer into the tool-side changer 128 and the arm-side changer 126 is as follows. First, with the robot arm 14 and the inner diameter measuring device 100 integrated, the inner diameter measuring device is stored in the tool holder 122. In this state, the stopper (not shown) provided on the hand changer is released. This release is performed in response to a command from the robot controller 12.

[0046] Through the above steps, the installation, replacement, and removal of the robot arm 14 relative to the inner diameter measuring device 100 are automated.

[0047] The robot 10 first measures the number of holes of the same nominal diameter on the workpiece 150 specified by the robot controller 12. It then switches to another internal diameter measuring device 100 to measure holes of different nominal diameters. It should be noted that deploying multiple robots 10, each equipped with an internal diameter measuring device 100 of a different nominal diameter, can further improve measurement efficiency.

[0048] Next, use Figure 2 and Figure 3 An embodiment of the inner diameter measuring device 100 will be described. Figure 2 FIG is a perspective view of the inner diameter measuring device 100. Figure 2 As shown, the inner diameter measuring device 100 generally includes a plug gauge 200 , a floating clearance unit 300 , a data conversion and transmission unit 400 , and a robot replacement unit 500 .

[0049] The plug gauge 200 is inserted into the holes 152 and 154 formed in the workpiece 150. The plug gauge 200 includes a cylindrical plug gauge body 260, a plurality of stoppers 262, and at least two measuring element holes 272. The stoppers 262 and measuring element holes 272 are arranged approximately evenly spaced along the circumference. Furthermore, each measuring element hole 272 contains a measuring element 270 that abuts against the holes 152 and 154, respectively.

[0050] The floating relief unit 300 is located above the feeler gauge 200 and allows for and compensates for positional deviations of the feeler gauge 200. The floating relief unit 300 also uses a built-in measuring device 380 to detect the displacement of the measuring member 270. The floating relief unit 300 includes a floating elastic body 350, which is mounted on a cylindrical bushing seat 340.

[0051] The data conversion and transmission unit 400 is located above the floating clearance unit 300. The data conversion and transmission unit 400 is covered by a cylindrical main body cover 422 and has a flange 424 on the upper portion. The data conversion and transmission unit 400 converts the analog data related to the displacement of the measuring member 270 into digital data representing the inner diameter of the holes 152 and 154. Figure 3 ) obtains analog data related to the displacement of the measuring piece. The data conversion and transmission unit 400 transmits the digital data representing the inner diameter to the robot controller 12 (equivalent to an external device). The measuring device 380 is built into the floating yielding unit 300. In the working environment of the robot arm 14, it is difficult to accurately transmit and receive analog data due to the presence of electromagnetic noise. However, in this embodiment, because the data conversion and transmission unit 400 is located directly above the measuring device 380, the transmission distance and time of the analog data are the shortest. In addition, because the measurement data is sent from the data conversion and transmission unit 400 to the external device as digital data that is not easily interfered by electromagnetic noise, more accurate and stable measurements can be performed.

[0052] The plug gauge 200 is a commercially available plug gauge, such as a BMD plug gauge manufactured by DIATEST of Germany. The plug gauge 200 has through holes formed at multiple locations on the side of the cylinder. The through holes are measuring piece holes 272.

[0053] Measuring member 270 extends through measuring member hole 272. Measuring member 270 is movable along the cylinder's radius. The radial displacement of measuring member 270 is converted into vertical movement of a built-in needle. The needle extends vertically on the back side of measuring member 270 (toward the center of the feeler gauge 200). The needle is tapered.

[0054] It should be noted that a force pushing radially outward from the cylinder is constantly applied to the measuring element 270. This force utilizes the elasticity of the needle. Therefore, under normal conditions, the measuring element 270 always protrudes from the outer circumference of the feeler gauge 200 by approximately 0.1 to 0.2 mm.

[0055] A measuring device 380 is arranged inside the floating relief portion 300. The measuring device 380 is connected to the needle of the plug gauge 200 or is arranged above the plug gauge shaft 210 which is integrated with the needle.

[0056] In this way, the needle displacement becomes the input of the measuring device 380. The displacement signal from the measuring device 380 is sent to the data conversion and transmission unit 400. The measuring device 380 can be a differential transformer displacement meter. It should be noted that in addition to the differential transformer displacement meter, the measuring device 380 can also use an optical ruler displacement meter using laser light, a pneumatic micrometer, and the like.

[0057] The gauge 380 is positioned at the center of the cylindrical floating clearance portion 300. Three clearance shafts 362 are arranged concentrically with the gauge 380 and on its outer periphery. The clearance shafts 362 extend vertically at intervals along the circumference. In this example, there are three clearance shafts 362, but the number of clearance shafts 362 may be greater. A ball bushing 364 is inserted into the vertical center of the clearance shaft 362. A spring 370 is also inserted into the clearance shaft 362. The lower end surface of the spring 370 contacts the upper end surface of the ball bushing 364.

[0058] The ball bushings 364 are held in three vertical through-holes. These through-holes are formed circumferentially on the cylindrical bushing seat 340, corresponding to the yield shafts 362. In this example, there are three vertical through-holes, but their number can be varied to match the number of yield shafts 362.

[0059] The bushing seat 340 extends downward in the vertical direction, passing over the lower end of the ball bushing 364. The yield shaft 362 is loosely fitted in the aforementioned hole that passes over the lower end of the ball bushing 364. An annular spring retaining plate 372 is arranged on the upper surface of the bushing seat 340. The spring retaining plate 372 has at least three through holes extending vertically therethrough. The spring 370 is loosely fitted in the through holes, with the lower end of the spring 370 retained. To retain the upper end of the spring 370, an annular pressure plate 374 is arranged vertically at a distance from the spring retaining plate 372. The upper end of the yield shaft 362 is fixed to the pressure plate 374. The gap between the spring retaining plate 372 and the pressure plate 374 is 4 to 5 mm. The pressure plate 374 is connected to the bottom flange of the data conversion and transmission unit 400.

[0060] An outer cylinder bracket 354 is arranged between the cylindrical ball bushing 364 and the measuring instrument 380. The outer cylinder bracket 354 is in the shape of a cylinder with a flange on the lower side. The upper end of the outer cylinder bracket 354 extends to a position slightly lower than the upper end of the ball bushing 364. The inner cylinder bracket 330 is embedded on the inner side of the outer cylinder bracket 354. The inner cylinder bracket 330 is in the shape of a cylinder with a flange formed in the middle of the axial direction. A pressure plate 332 is installed on the upper surface of the inner cylinder bracket 330 with a fixing screw 334. The flange portion of the outer cylinder bracket 354 is supported on the upper surface of the flange located in the middle of the axial direction of the inner cylinder bracket 330. The inner cylinder bracket (plug gauge bracket) 330 holds the output shaft of the plug gauge 200 at the lower part.

[0061] The bushing seat 340 has multiple notches for mounting the floating elastic body 350. These notches are formed at locations circumferentially other than the hole for the yield shaft 362. Furthermore, the notches are formed at multiple locations along the circumference and extend vertically. The floating elastic body 350 is mounted in these notches using screws 352, 352.

[0062] That is, notches are formed at multiple locations around the circumference of the bushing seat 340. A floating elastic body 350 of a size corresponding to the notch is installed at the notch. The upper end of the floating elastic body 350 is installed on the bushing seat 340. In addition, the lower end is installed on the flange portion of the outer cylindrical bracket 354. The installation is performed using screws 352. The floating elastic body 350 is elastic and has a cubic, cylindrical, or cylindrical shape. Its material can be rubber, plastic, or a combination thereof. The floating elastic body 350 can be a coil spring. Its material can be metal, reinforced plastic, etc.

[0063] The following describes the operation of the thus configured floating clearance unit 300. First, the inner diameter measuring device 100 is mounted on the top of the robot arm 14. Then, using a preprogrammed method, the robot arm 14 is brought close to the workpiece 150 having holes 152 and 154. Following the program, the plug gauge 200 of the inner diameter measuring device 100 is positioned above the holes 152 and 154. The plug gauge 200 is then lowered toward the holes 152 and 154.

[0064] At this time, the center of the holes 152, 154 formed on the workpiece 150 and the center of the plug gauge 200 will deviate within the allowable error. The cylindrical portion of the plug gauge 200 below the stopper 262 acts as a guide portion 264 when inserting the plug gauge 200 into the holes 152, 154. The gap (clearance) formed by the outer diameter of the guide portion 264 of the plug gauge 200 and the inner diameter of the holes 152, 154 is usually several tens of μm. Therefore, the guide portion 264 descends while making a part of it contact with the inner wall of the holes 152, 154. At this time, if the force of the guide portion 264 pressing the wall of the hole 152, 154 increases due to coaxial deviation, or if only a part of the guide portion 264, such as the corner, contacts the wall when the guide portion 264 is inserted at an angle, a large pressure will be applied to the contact portion. In this way, if the pressing force during contact increases due to coaxial deviation, the guide portion 264 may sometimes be stuck with the holes 152 and 154, which may hinder automatic measurement.

[0065] Therefore, in this embodiment, a plurality of floating elastic bodies 350 are provided on the bushing seat 340. The floating elastic bodies 350 automatically displace or move the feeler gauge 200 in a direction to reduce the contact force according to the contact force between the guide portion 264 and the inner wall of the hole 152, 154. The floating elastic bodies 350 can move along the Figure 3 The feeler gauge 200 elastically deforms in the horizontal direction of the paper. Therefore, even if the center of the feeler gauge 200 is offset to the left or right from the center of the hole 152 or 154 (or tilted relative to the vertical axis) and inserted into the hole 152 or 154, the feeler gauge 200 and the inner cylindrical retainer 330 will tilt along with the hole 152 or 154. This is caused by the elastic deformation of the floating elastic body 350. As a result, the center of the feeler gauge 200 is aligned with the center of the hole 152 or 154. As a result, the feeler gauge 200 can be inserted deeper into the hole 152 or 154 for measurement.

[0066] The coaxial deviation of the plug gauge 200 relative to the holes 152, 154 generally has a component in a direction perpendicular to the vertical direction. In other words, the coaxial deviation has Figure 3Components in the left and right directions of the paper. In other words, if the vertical direction is set as the z direction, the coaxiality deviation has x and y components perpendicular to the z direction. Therefore, one or more floating elastic bodies 350 are arranged along the circumference of the bushing seat 340 to cope with the coaxiality deviation in the x and y directions. There is no restriction on the deformation direction of the floating elastic body 350, and one floating elastic body 350 can be used to cope with the coaxiality deviation in the x and y directions. If three or more floating elastic bodies 350 are arranged along the circumference, the bushing seat 340 and the outer cylindrical support 354 and the inner cylindrical support 330 can easily change their positions while maintaining a nearly parallel state. To determine the plane, at least three fixed points are required. In the method of arranging three or more floating elastic bodies 350 along the circumference, the rotation relative to the x-axis and y-axis is further restricted, resulting in a more accurate compensation for the coaxiality deviation. There is no special limitation on the arrangement of multiple floating elastic bodies 350, and it is preferred to arrange them at equal intervals in the circumferential direction. For example, if three are arranged, a spacing of approximately 120° is preferred.

[0067] As described above, in the floating clearance portion 300 serving as the connection portion, the floating elastic body 350 , the bushing seat 340 , and the inner cylindrical support 330 form a floating mechanism.

[0068] The ball bushings 364 are mounted on three yield shafts 362. The three yield shafts 362 are located at different circumferential positions than the floating elastic body 350. In other words, the ball bushings 364 are located at different circumferential positions than the floating elastic body 350. The ball bushings 364 are movable vertically along the yield shafts 362. When excessive force is applied to the inner cylindrical retainer 330, the bushing seat 340 moves up and down, causing the feeler gauge 200 to move up and down. Excessive force can occur, for example, when the guide portion 264 of the feeler gauge 200 contacts the inner surfaces of the holes 152 and 154. The vertical movement of the bushing seat 340 is achieved by the spring force of the spring 370. This vertical movement of the bushing seat 340 is achieved by the outer cylindrical retainer 354 supported by the inner cylindrical retainer 330. This causes the feeler gauge 200 to yield. The yielding shaft, at least three ball bushings 364 and the spring 370 constitute a yielding mechanism.

[0069] The floating yielding portion 300 (connecting portion) includes a yielding mechanism, a floating mechanism, and a measuring device 380. The floating yielding portion 300 is an integrated component with the measuring device 380 as the center portion, and the floating mechanism and the yielding mechanism arranged on its periphery. Compared with the prior art, the integration can shorten the axial length (the length in the vertical direction) of the floating yielding portion 300, thereby achieving compactness. In this way, the moment load applied to the robot arm 14 can be reduced. It is particularly beneficial to install the inner diameter measuring device 100 on the top portion of the robot arm 14 and move it to the measuring position. By achieving compactness, it is also more suitable for storage on the tool bench 130. In addition, the tool replacement operation also becomes easier.

[0070] Next, a method of measuring the inner diameters of the holes 152 and 154 of the workpiece 150 using the inner diameter measuring device 100 will be described.

[0071] First, an inner diameter measuring device 100 corresponding to the diameter of the holes 152 and 154 is mounted on the top of the robot arm 14. The inner diameter measuring device 100 is automatically selected from the tool table 130 and mounted by the robot 10.

[0072] Next, the inner diameter measuring device 100 is calibrated using a reference member (not shown). The robot 10 rotates and translates the arm 14 until it is brought to the vicinity of the workpiece 150 at a predetermined position on the conveyor 140. The feeler gauge 200 of the inner diameter measuring device 100 is then positioned above the holes 152 and 154.

[0073] Next, the robot 10 slowly inserts the inner diameter measuring device 100 into the holes 152, 154, using the guide portion 264 of the plug gauge 200 as a guide. At this point, coaxial deviation occurs within the allowable error between the guide portion 264 and the holes 152, 154. This coaxial deviation between the plug gauge 200 and the holes 152, 154 is compensated for by the floating mechanism. Specifically, the floating mechanism displaces the floating relief portion 300, automatically aligning the plug gauge 200 within the holes 152, 154.

[0074] Then, the feeler gauge 200 is lowered to a position where the stopper 262 takes effect or to a preset measuring depth position.

[0075] Measurement then begins at this position, and the displacement of the measuring member 270 is transmitted to the measuring device 380 as mechanical deformation. The measuring device 380 converts the deformation (displacement) into an electrical signal (analog data). The data conversion and transmission unit 400 converts the electrical signal (analog data) representing the displacement obtained by the measuring device 380 into digital data representing the inner diameter of the holes 152 and 154. The digital data is transmitted to the robot 10 via the data cable 508 and the electrode device 510. The digital data is ultimately stored in the robot controller 12 or an attached storage device.

[0076] Here, the force pushing outward from the measuring member hole 272 of the plug gauge 200 constantly acts on the measuring member 270. When the plug gauge 200 is not in contact with anything else (normal state), the measuring member 270 protrudes from the plug gauge 200 by approximately 0.2 mm due to this force. The tip of the measuring member 270 is hemispherical. Therefore, even if the measuring member 270 contacts the inner wall of holes 152 or 154 while protruding approximately 0.2 mm, it will not become stuck due to the downward force of the plug gauge 200. Instead, it will follow the inner wall surface, overcoming the aforementioned force, and be drawn into the plug gauge.

[0077] Sometimes the lowering action of the plug gauge 200 is stopped midway and pulled up. For example, when the holes 152 and 154 formed on the workpiece 150 are formed outside the allowable range due to poor processing, and when the hole position deviates from the expected range. The above-mentioned action can be implemented by using the yielding mechanism of the floating yielding part 300. However, the function of the yielding mechanism is to passively contract under the action of excessive external force. Therefore, there are limitations to achieving pulling. For example, there is a method that utilizes the fact that the force used to make the yielding mechanism work is stronger than the normal insertion action. That is, for example, there is the following method: setting it so that once the robot detects an abnormal load (to the extent that the yielding mechanism will work) during the insertion action, it will pull up.

[0078] The following describes tool replacement. For example, in batch processing, tool replacement is performed for each batch. Furthermore, when continuously measuring workpieces continuously transported by a conveyor, for example, tool replacement is performed after a predetermined number of workpieces. The holes 152 and 154 of the workpiece 150 are changed every predetermined number of workpieces. Specifically, a predetermined number of small-diameter holes 152 on the workpiece 150 are measured first, and then, when the larger-diameter hole 154 is to be measured, the tool is replaced during this switch.

[0079] On the tool stage 130 , the inner diameter measuring devices 100 having different measurable ranges are stored on the tool holder 122 .

[0080] First, the inner diameter measuring device 100 corresponding to the small-diameter hole 152 is installed at the top of the robot arm 14. The installation is automatically performed by the robot 10 receiving a command from the robot controller 12. Then, the inner diameters of the holes 152 of a predetermined number of workpieces 150 are measured.

[0081] The robot arm 14 is then rotated and translated to guide it toward the empty tool holder 122. A stopper (not shown) is then released, separating the robot arm-side changer 126 from the tool-side changer 128. In this state, only the robot arm-side changer 126 is attached to the tip of the robot arm 14. The robot arm 14 is then moved and positioned on a predetermined tool holder 122. This tool holder 122 houses an inner diameter measuring device 100 corresponding to a large-diameter hole 154 to be measured. A new inner diameter measuring device 100 is then attached to the tip of the robot arm 14, enabling measurement of the large-diameter hole 154.

[0082] Another embodiment of the inner diameter measuring device will be described below. Figure 4 It is a perspective view of the main parts of another embodiment of the inner diameter measuring device. Figure 5 yes Figure 4 An explanatory diagram of a tilt compensation method for an inner diameter measuring device shown.

[0083] Figure 4 The illustrated inner diameter measuring device 102 differs from the above-described embodiment primarily in two key aspects. First, the plug gauge is integrated with the connecting portion, further simplifying the structure. Second, positional deviations of the inner diameter measuring device 102 (measuring element 270) relative to the holes 152 and 154 are compensated for. This is achieved by providing four (or more) measuring elements 270.

[0084] The inner diameter measuring device 102 is composed, for example, of two displacement measuring devices described in Japanese Patent Application Publication No. 2018-169180 (Patent Document 6). The data conversion and transmission unit 410 has the same configuration as the above-described embodiment. Four displacement measuring devices 381 are connected to the data conversion and transmission unit 410. Displacement measuring devices 381 are, for example, linear variable differential transformers (LVDTs) or optical scale displacement meters.

[0085] A finger 383 extending in the vertical direction is provided at the lower end of the displacement measuring device 381. Measuring elements 270 for measuring displacement are mounted on the fingers 383, respectively.

[0086] An outward force is constantly applied to each measuring element 270. This force is applied by an elastic body through finger-shaped members 383. Normally, the radius of the enveloping circle connecting the tips of each measuring element 270 is approximately 0.1 to 0.5 mm larger than the maximum inner radius of the hole being measured. This allows for measurement even when considering variations in inner radius tolerance and coaxiality.

[0087] The top end of measuring member 270 is hemispherical. When inner diameter measuring device 102 is inserted into holes 152, 154, the hemispherical portion of measuring member 270 contacts the inner surface of holes 152, 154. It should be noted that a further function is possible: using a built-in air cylinder (not shown), for example, the finger 383 of displacement measuring device 381 is forced to retract (move radially inward by several millimeters). Inserting the finger 383 into the hole in this retracted state prevents the finger from contacting the hole, even if the hole is slightly misaligned or the workpiece is not properly machined.

[0088] The following describes a method for measuring the inner diameter of holes 152, 154 using the inner diameter measuring device 102, including: Figure 5 Compensation method shown.

[0089] First, the inner diameter measuring device 102 is pre-calibrated using a reference object. The center of the reference object is aligned with the center of the inner diameter measuring device. When the centers are aligned, the output of the displacement measuring device 381 (calibration data) is obtained based on the displacement of each measuring member 270.

[0090] Next, the inner diameter measuring device 102 is inserted into the hole 152 of the workpiece 150. During the insertion, the inner diameter measuring device 102 may be inserted with its central axis tilted relative to the central axes of the holes 152, 154.

[0091] Figure 5 15 is an explanatory diagram showing the relationship between the hole 152 and the inserted inner diameter measuring device 102A. Figure 5 The state in which the center axis of the inner diameter measuring device 102A is inserted with an inclination relative to the center axis of the hole 152 is shown. Figure 5 The inner diameter measuring device 102A shown by the solid line in FIG. 1 shows a state in which it is shallowly inserted into the hole 152. The inner diameter measuring device 102B shown by the dotted line in FIG.

[0092] Comparing inner diameter measuring devices 102A and 102B reveals that the amount of retraction (displacement) of each measuring member varies with insertion depth. As the inner diameter measuring device is inserted into hole 152, measuring member 270A is pushed inward. Furthermore, as the inner diameter measuring device is inserted into hole 152, measuring member 270B is pushed outward. For more accurate inner diameter measurement, it is preferable to compensate the measured value based on slope θ.

[0093] The slope θ is unknown when the measurement is first inserted. To compensate for the measured value, the slope θ must first be calculated. The method is as follows.

[0094] First, in a cross section including the center axis of the measuring piece and the inner diameter measuring device, the slope θ of the inner diameter measuring device 102 is calculated using the following formula using the insertion amount x and the change Δy in the measured value. (Formula) θ = tan-1(Δy / x)

[0095] The change in measured value Δy is typically caused by the slope of the inner diameter measuring device. However, in principle, the change Δy can also occur due to factors other than the slope of the inner diameter measuring device. For example, this can occur when holes 152 and 154 are tapered or when the inner diameter of holes 152 and 154 varies along the depth direction. In order to distinguish the changes caused by the above situation from the changes caused by the tilt of the inner diameter measuring device, the slope θ is preferably calculated based on the average value of the outputs of a pair of measuring members 270A and 270B arranged with a phase difference of 180°.

[0096] After calculating the slope θ in this manner, the robot 10 rotates the inner diameter measuring device 102 to eliminate the slope θ.

[0097] Because inner diameter measuring device 102 can be inserted along the central axis of holes 152 and 154, it is inserted to the specified measurement depth. The displacements (analog data) of the four measuring members 270 are then transmitted to displacement measuring device 381. Data conversion and transmission unit 400 converts the displacements into digital data representing the inner diameter and transmits the data to the robot controller.

[0098] According to this embodiment, the positioning accuracy of the robot 10 for the inner diameter measuring device 102 can be made rough. Therefore, the man-hours required for teaching can be reduced. Moreover, if the reference part is aligned with the center of the inner diameter measuring device 102 during the reference calibration (zero point calibration) of the inner diameter measuring device 102, then when measuring the inner diameter of the holes 152 and 154 formed on the workpiece 150, the inner diameter and center position of the holes 152 and 154 can be obtained by comparison with the calibration using the reference part. The center position of the holes 152 and 154 can be used as the measurement result of the workpiece 150 or for position compensation for teaching of the robot 10. In addition, because the movable displacement of the measuring part 270 can be made larger, the replacement frequency of the inner diameter measuring device 102 can be reduced. As a method, the movable displacement can be increased with an upper limit of 0.5 to 2 mm.

[0099] Furthermore, in each of the above-described embodiments, by minimizing the distance between the measurement point and the data conversion and transmission unit, the adverse effects of noise on measurement caused by the industrial robot, particularly the servo motors used therein, can be reduced. Furthermore, because the data is converted to digital data before being transmitted externally, data degradation caused by noise surrounding the robot can be prevented, improving noise immunity.

[0100] The inner diameter measuring device of this embodiment also includes a data conversion and transmission unit that converts the detection signal from the measuring piece into digital data. This allows for reliable preservation of the detection signal and measurement data, even when electromagnetic noise is generated in the robotic arm on which the inner diameter measuring device is mounted and its surroundings. Furthermore, because the inner diameter measuring device utilizes a floating mechanism that allows lateral displacement of the measuring unit, it can be smoothly inserted into the hole even if the angle between the measuring unit and the horizontal plane deviates, thereby preventing damage and scratches to the measuring piece and the hole. Furthermore, because the inner diameter measuring device utilizes an upper end structure compatible with an automatic tool changer, it is possible to measure the inner diameter of holes of varying inner diameters by preparing inner diameter measuring devices with different measurement ranges. Furthermore, because the three mechanisms—the yield mechanism, the floating mechanism, and the measuring mechanism—are integrated into the inner diameter measuring device, a robot-use inner diameter measuring device with a shorter overall length (vertical length) is achieved, thereby reducing the moment load on the end of the robotic arm when it rotates. - Explanation of symbols - 10. Robot 12 Robot Controller 14 Robotic Arm 16 Wiring 50 Internal diameter measuring system 100, 102 inner diameter measuring device 122 Tool Stand 124 guide part 126 (Robot arm side) Changer 128 (Tool side) Changer 130 Tool Bench 140 Conveyor 150 workpiece (object to be measured) 152 holes (small diameter side) 154 holes (large aperture side) 200 plug gauge 210 plug gauge shaft 260 plug gauge body 262 stopper 264 guide part 270 measuring pieces 272 measuring hole 300 Floating clearance part (connection part) 330 (Inner Cylindrical Retainer) Plug Gauge Retainer 332 pressure plate 334 fixing screw 340 bushing seat 350 (Floating) Elastomer 352 screws 354 (outer) cylindrical cage 362 Yield Axis 364 Ball Bushing 370 Spring 372 Spring retaining plate 374 pressure plate 380 Measuring Instrument 381 Displacement Measuring Device 383 finger 400, 410 Data conversion and transmission unit 422 main body cover 424 flange 500 Robot replacement unit 508 data cable 510 Electrode device.

Claims

1. An inner diameter measuring device, detachably mounted on the top end of a robotic arm, for measuring the inner diameter of a hole formed in a workpiece, characterized in that: The inner diameter measuring device includes at least two measuring pieces and a data conversion and transmission unit. The at least two measuring members abut against the inner wall surface of the hole formed on the workpiece, The data conversion and transmission unit converts analog data related to the displacements of the at least two measuring members into digital data representing the inner diameter of the hole and transmits the digital data to an external device.

2. The inner diameter measuring device according to claim 1, characterized in that: The data conversion and transmission section transmits the digital data to the external device connected via a wire.

3. The inner diameter measuring device according to claim 1, wherein: The inner diameter measuring device includes a plug gauge and a connecting portion, wherein the plug gauge holds the at least two measuring members at the top end. The connecting portion is provided between the plug gauge and the data conversion and transmission portion. The connecting portion is configured to allow the robot arm to be displaced relative to the feeler gauge in an axial direction and a direction substantially perpendicular to the axial direction.

4. The inner diameter measuring device according to claim 3, characterized in that: The connecting portion is formed into an overall vertically long cylindrical shape, and includes a bushing seat formed into an annular shape, a floating mechanism, a position-releasing mechanism and a measuring mechanism respectively retained in the bushing seat, The floating mechanism allows the robot arm to move in a direction substantially perpendicular to the axial direction. The yield mechanism allows the robot arm to perform the displacement in the axial direction. The measuring mechanism acquires the simulation data, The measuring mechanism is arranged at the center of the bushing seat, and the floating mechanism and the yielding mechanism are arranged around the measuring mechanism.

5. The inner diameter measuring device according to claim 4, characterized in that: The said giving way mechanism comprises at least three ball bushings and bushing shafts, wherein the at least three ball bushings are arranged at intervals along the circumference of the bushing seat. The bushing shaft is disposed relative to each of the ball bushings and passes through a center portion of the ball bushing.

6. The inner diameter measuring device according to claim 4, characterized in that: The floating mechanism includes an elastic body, and one end portion of the elastic body is locked on the bushing seat.

7. The inner diameter measuring device according to claim 1, characterized in that: The at least two measuring elements are four measuring elements, The inner diameter measuring device includes a displacement measuring device connected to the four measuring members respectively. The four measuring pieces are arranged at intervals along the circumferential direction. The data conversion and transmission unit converts the analog data detected by the displacement measuring device into digital data indicating the inner diameter of the hole and transmits the digital data to the external device.

8. An inner diameter measuring system, characterized in that: The inner diameter measuring system includes the robot arm and the inner diameter measuring device according to any one of claims 1 to 7.

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