Workpiece outer diameter measuring device

Abstract

To facilitate maintenance and to permit easy and precise measurement of outer shape dimensions of a workpiece.SOLUTION: While a workpiece 2 is supported from a lower side by two conveyance belts 3 and is conveyed in the direction of an axial center, an outer shape of the workpiece 2 is measured by a measuring instrument 16. An outer shape measuring device includes the measuring instrument 16 for capturing the workpiece 2 including an upper outer shape section 23 and a lower outer shape section 24 of the workpiece 2 as a side surface two-dimensional image 21 from a direction nearly orthogonal to the direction of an axis center of the workpiece 2 on the conveyance belts 3, the conveyance belts 3 of a measurement section 5 in which the measuring instrument 16 is disposed are spaced such that the upper outer shape section 23 and the lower outer shape section 24 projects to both the upper and lower sides of the conveyance belts 3, and the conveyance belts 3 in an upstream side of at least the measurement section 5 are spaced narrower than the interval between the conveyance belts 3 of the measurement section 5.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a workpiece outer shape measuring apparatus for measuring the outer diameter dimension, outer shape dimension, outer shape, and other outer profiles of a workpiece such as a tapered shaft.

Background Art

[0002] As a workpiece outer shape measuring apparatus that measures the outer diameter of a small-diameter workpiece such as a tapered shaft after grinding the outer periphery of the workpiece, there is one described in Patent Document 1. This conventional outer shape measuring apparatus is provided with an adhering matter removing section and a measuring section along two left and right conveyor belts such as wire belts that support the workpiece from the lower side and convey the workpiece in the workpiece axial direction. The adhering matter removing section blows air onto the workpiece from both upper and lower sides to remove adhering matter such as coolant, and in the measuring section, a vertically projecting measuring instrument projects laser light onto the workpiece after the adhering matter is removed, so as to measure the outer diameter dimension of the workpiece.

[0003] The measuring instrument includes a light projecting unit disposed on the upper side or the lower side of the two conveyor belts, and a light receiving unit disposed on the opposite side facing the light projecting unit. The light receiving unit receives the laser light projected vertically from the light projecting unit to the workpiece, so as to measure the outer diameter dimension of the workpiece. Further, the interval between the left and right conveyor belts is narrowed in the measuring section so that each conveyor belt does not protrude to both left and right sides of the workpiece, and is widened in the adhering matter removing section on the upstream side of the measuring section.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventional external shape measuring devices have a light-emitting unit and a light-receiving unit on both the upper and lower sides of two conveyor belts. Therefore, either the light-emitting unit or the light-receiving unit must be positioned on the lower side of the two conveyor belts. Although deposits such as coolant are removed in the deposit removal unit upstream of the measuring unit, in environments where fine particles such as coolant are scattered, the lens system of the lower light-emitting or light-receiving unit becomes significantly contaminated, requiring frequent maintenance to obtain highly accurate measurement results.

[0006] Furthermore, because the workpiece on the conveyor belt is measured by projecting laser light using an overhead projection type measuring instrument, there is a problem in that the outer shape of the workpiece cannot be accurately measured if there is variation in the inclination of the workpiece within the vertical plane during conveyance.

[0007] Furthermore, the spacing between the two conveyor belts is narrowed in the measuring section so that each conveyor belt is not exposed on either side of the workpiece, while it is wider in the adhering material removal section. Therefore, in the case of small-diameter workpieces such as tapered shafts, in the adhering material removal section where the spacing between the conveyor belts is wide, the small-diameter side of the workpiece is more likely to get stuck between the conveyor belts due to its own weight, vibration, etc. In addition, the spacing between the conveyor belts may widen due to air being blown onto the workpiece from above, and there is a risk that the workpiece may fall downward from between the conveyor belts.

[0008] Furthermore, if the smaller diameter portion of the workpiece gets caught between the conveyor belts, vibrations and other forces can cause a large external force to spread the conveyor belts apart. As a result, in external diameter measuring devices targeting small-diameter workpieces, very thin conveyor belts such as wire belts of 0.45 mm or less are used, which can lead to problems such as the conveyor belts being easily cut.

[0009] In view of these problems, the present invention aims to provide a workpiece outer shape measuring device that facilitates maintenance of the measuring instrument, prevents a decrease in measurement accuracy due to variations in the workpiece's orientation, and stably transports the workpiece while preventing damage to the conveyor belt. [Means for solving the problem]

[0010] The present invention relates to a workpiece outer shape measuring device that supports a workpiece from below with two conveyor belts and conveys it in the axial direction while measuring the outer shape of the workpiece with a measuring instrument, wherein the measuring instrument captures the workpiece, including the upper and lower outer shapes, as a two-dimensional side image from a direction substantially perpendicular to the axial direction of the workpiece on the conveyor belts, and the conveyor belts of the measuring section where the measuring instrument is located are spaced such that the upper and lower outer shapes protrude from both the upper and lower sides of the conveyor belts, and at least the conveyor belt upstream of the measuring section is spaced narrower than the spacing between the conveyor belts of the measuring section.

[0011] Preferably, the side two-dimensional image includes an upper outer shape image of the upper outer shape portion extending from both ends in the axial direction of the workpiece to the upper portion, and a lower outer shape image of the lower outer shape portion extending from both ends in the axial direction of the workpiece to the lower portion. Preferably, the workpiece has an outer shape calculation unit that calculates the outer shape of the workpiece, including the upper and lower outer shapes, from the side two-dimensional image. Preferably, the workpiece has an outer diameter dimension calculation unit that calculates the outer diameter dimension between the upper and lower outer shapes of the workpiece from the side two-dimensional image.

[0012] Upstream of the measuring section, there is a deposit removal section for removing deposits from the workpiece during transport, and it is desirable that the conveyor belt of the deposit removal section be spaced narrower than the wider spacing between the conveyor belts of the measuring section. It is desirable that the spacing between the conveyor belts on the measuring section side of the deposit removal section gradually widens from the narrow spacing on the deposit removal section side to the wider spacing of the measuring section, and that the spacing between the conveyor belts downstream of the measuring section gradually narrows from the wide spacing of the measuring section. It is desirable that at least the outer peripheral contact portion of the workpiece that contacts the conveyor belt is concentric with respect to the axis of the workpiece. [Effects of the Invention]

[0013] According to the present invention, maintenance of the measuring instrument can be easily performed, a decrease in measurement accuracy due to variations in the posture of the workpiece can be prevented, and the workpiece can be transported stably while preventing damage to the conveyor belt. [Brief explanation of the drawing]

[0014] [Figure 1] This is a side view of an external shape measuring device showing one embodiment of the present invention. [Figure 2] The same plane diagram. [Figure 3] (a) to (c) are explanatory diagrams of the workpiece and the conveyor belt. [Figure 4] This is a diagram illustrating the spacing of the conveyor belt. [Figure 5] (a) to (c) are explanatory diagrams of the laser light, projection area, and projected image. [Figure 6] (a) to (d) are explanatory diagrams of the same workpiece. [Best Mode for Carrying Out the Invention]

[0015] Embodiments of the present invention will be described in detail below with reference to the drawings. Figures 1 to 6 illustrate an external shape measuring device 1 for measuring the outer diameter of a workpiece. This external shape measuring device 1 is used to measure the outer diameter X in the direction perpendicular to the axis Y of a workpiece 2 that has been ground by a centerless grinding machine, and to sort the workpiece 2 into good products and defective products according to the measurement results. As shown in Figures 1 and 2, it comprises two conveyor belts 3 that continuously convey the workpiece 2 in the direction of its axis, a workpiece 2 input chute 4 located at the uppermost side of the conveyor belts 3, a measuring unit 5 located downstream of the conveyor belts 3, a deposit removal unit 6 located downstream of the input chute 4 and upstream of the measuring unit 5, and a discharge unit 7 located downstream of the measuring unit 5.

[0016] The workpiece 2 is, for example, as shown in FIGS. 3(a) to 3(c), a small-diameter tapered shaft whose outer peripheral surface is ground into a tapered shape. The outer peripheral surface of this workpiece 2 is concentric with its axis Y. When measuring the outer diameter dimension X in the direction perpendicular to the axis Y of the workpiece 2, the measurement site of the outer diameter dimension X may be one location in the axial direction, or may be a plurality of locations.

[0017] As shown in FIGS. 3(a) to 3(c), the conveyor belt 3 is for supporting the workpiece 2 from the lower side and continuously conveying it in the axial direction (the direction indicated by arrow A), and is constituted by a single endless wire belt with a round cross-section, and is in contact with the outer peripheral surface over substantially the entire axial length of the workpiece 2 to support it from the lower side. The conveyor belt 3 is formed by crossing one wire belt once to form two loops, and is wound around the drive pulley 8 and the driven pulley 9 such that the conveying sides, which are the upper sides of the respective loops, are parallel to each other on the left and right. The drive pulley 8 is driven in the direction indicated by arrow B by the drive motor 10. The conveying side of the conveyor belt 3 is guided by intermediate pulleys 11, 12 disposed on the upstream side and the downstream side of the deposit removing unit 6, and measuring unit pulleys 13, 14 disposed on the upstream side and the downstream side of the measuring unit 5, and the intermediate portion on the conveying side is gently curved upward in an arc shape.

[0018] As shown in FIG. 4, the drive pulley 8, the driven pulley 9, the intermediate pulleys 11, 12, and the measuring unit pulleys 13, 14 are provided with two left and right guide grooves 8a, 9a, 11a to 14a, and the guide grooves 8a, 9a, 11a to 14a guide the two conveyor belts 3 while maintaining the interval therebetween at a predetermined interval. In addition, escape portions 8b, 9b, 11b to 14b are provided between the two guide grooves 8a, 9a, 11a to 14a of each of the pulleys 8, 9, 11 to 14 so as not to interfere with the workpiece 2. On the return side, which is the lower side of the conveyor belt 3, a tension pulley 15 is provided corresponding to each one of the conveyor belts so that the tension of the entire conveyor belt 3 can be adjusted.

[0019] In this way, the driving pulley 8, driven pulley 9, intermediate pulleys 11 and 12, and measuring unit pulleys 13 and 14 guide the conveying side of the conveyor belt 3 in an upward arcuate shape, and by providing the tension pulley 15, sagging on the conveying side of the two conveyor belts 3 can be prevented, so that the workpiece 2 can be smoothly guided in the axial direction of the workpiece. Note that the two conveyor belts 3 can also be configured by winding the conveying sides of two endless belts in parallel. In that case, a tension pulley 15 may be provided for each endless belt.

[0020] The deposit removing unit 6 is provided with an air blower 34 for blowing air to the workpiece 2 on the conveyor belt 3 from both upper and lower sides to remove coolant, dust and the like adhering to the surface of the workpiece 2, and the workpiece 2 is sent to the measuring unit 5 in a clean state after deposits are removed by the air from the air blower 34.

[0021] The measuring unit 5 has a left-right projection type measuring instrument 16 having a light projecting unit 17 and a light receiving unit 18 disposed on both left and right sides with the workpiece 2 on the conveyor belt 3 interposed therebetween. When measuring the outer diameter dimension X of the workpiece 2, the side shape of the workpiece 2 is projected from the left-right direction substantially orthogonal to the axial direction of the workpiece 2 on the conveyor belt 3, and captured as a side two-dimensional image 21 including the workpiece image 25. The light receiving unit 18 is connected to an outer diameter dimension calculating unit 22, and the outer diameter dimension calculating unit 22 is configured to calculate the outer diameter dimension X of the workpiece 2 from the workpiece image 25 in the side two-dimensional image 21.

[0022] As shown in FIGS. 5(a) and 5(b), the light projecting unit 17 irradiates countless laser beams 20 in a circular projection region 19 to the light receiving unit 18 in parallel in the left-right direction (horizontal direction). As shown in FIG. 5(c), the light receiving unit 18 receives the laser beams 20 from the light projecting unit 17, and captures a projected image of the portion shielded by the conveyor belt 3 and the workpiece 2 as a side two-dimensional image 21. The side two-dimensional image 21 includes a workpiece image 25 corresponding to the workpiece 2 and a belt image 26 corresponding to the conveyor belt 3.

[0023] As shown in Figure 4, the spacing D between the conveyor belts 3 in the measuring section 5 is wider than the spacing F between the conveyor belts 3 in the deposit removal section 6. The spacing D between the conveyor belts 3 in the measuring section 5 is such that, when the conveyor belts 3 transport the workpiece 2 of the measuring section 5, as shown in Figures 3(a) and 3(b), the upper outer shape 23 and lower outer shape 24 of the workpiece 2 protrude from both the upper and lower sides of the conveyor belt 3, and in a side view, the upper outer shape 23 and lower outer shape 24 of the workpiece 2 do not overlap with the conveyor belt 3.

[0024] As shown in Figure 5(b), the projection targets for measuring workpiece 2 are the upper outer shape 23 and lower outer shape 24 on both the upper and lower sides of the conveyor belt 3. The upper outer shape 23 includes the area from both ends 23a, 23b in the axial direction of workpiece 2 to the upper part 23c, and the lower outer shape 24 includes the area from both ends 24a, 24b in the axial direction of workpiece 2 to the lower part 24c.

[0025] Of the two-dimensional side view image 21 captured by the measuring instrument 16, the workpiece image 25 is a projected image having, as shown in Figure 5(c), an upper outer shape image 27 including end-end images 27a, 27b and upper side image 27c corresponding to each part of the upper outer shape 23 of the workpiece 2, and a lower outer shape image 28 including end-end images 28a, 28b and lower side image 28c corresponding to each part of the lower outer shape 24 of the workpiece 2.

[0026] The projection area for the upper outer shape 23 and lower outer shape 24 of workpiece 2 during measurement can be appropriately changed depending on the purpose and location of the calculation when determining the outer shape of workpiece 2. For example, if the purpose is to calculate the outer diameter dimension X at an arbitrary location, the ends 23a and 23b of the upper outer shape 23 and the ends 24a and 24b of the lower outer shape 24 are not necessarily required. In this case, the workpiece image 25 of the side two-dimensional image 21 can be obtained by targeting the upper part 23c of the upper outer shape 23 and the lower part 24c of the lower outer shape 24.

[0027] When measuring the workpiece 2 on the conveyor belt 3, the passage confirmation sensor 29 detects the passage of the workpiece 2, and when the workpiece 2 is positioned approximately in the center of the projection area 19 as shown in Figure 5(b), the measuring instrument 16 captures the workpiece 2 and the surrounding objects as a side view two-dimensional image 21. At this time, the workpiece 2 is on the conveyor belt 3, and the laser beam 20 is blocked by the workpiece 2 and the conveyor belt 3. Therefore, as shown in Figure 5(c), the side view two-dimensional image 21 includes a belt image 26 in addition to the workpiece image 25.

[0028] However, since the upper outer shape portion 23 and the lower outer shape portion 24 of the workpiece 2 protrude from both the upper and lower sides of the conveyor belt 3, the upper outer shape image 27 and the lower outer shape image 28 of the workpiece image 25 corresponding to the upper outer shape portion 23 and the lower outer shape portion 24, excluding the vicinity of the conveyor belt 3, do not overlap with the belt image 26. Therefore, it is possible to distinguish between the workpiece image 25 and the belt image 26 in the image processing of the side two-dimensional image 21, and the outer diameter dimension calculation unit 22 can extract the upper part image 27c corresponding to the upper part 23c of the workpiece 2 and the lower part image 28c corresponding to the lower part 24c of the workpiece 2 from the workpiece image 25 included in the side two-dimensional image 21, and calculate the outer diameter dimension X between the upper part 23c and the lower part 24c of the workpiece 2.

[0029] The side view two-dimensional image 21 may be an image of the light-shielding portion where the laser light 20 of the light-emitting unit 17 is blocked by the workpiece 2, as shown in Figure 5, or it may be an image of the light-receiving portion where the light-receiving unit 18 receives the laser light 20. In addition, the light-emitting unit 17 and the light-receiving unit 18 can use not only laser light 20 but also the light beam of a high-brightness LED, etc.

[0030] By using a left-right projection type measuring instrument 16 having a two-dimensional projection area 19, the measuring instrument 16 captures the workpiece 2 on the conveyor belt 3 as a left-right side two-dimensional image 21, and then calculates the outer diameter dimension X of the workpiece 2 by image processing of the side two-dimensional image 21. This allows for highly accurate measurement of the outer diameter dimension of the workpiece 2 without being affected by the orientation of the workpiece 2 on the conveyor belt 3 in the vertical plane.

[0031] In other words, when the workpiece 2 is a tapered shaft, the smaller diameter side of the workpiece 2 on the conveyor belt 3 is lower than the larger diameter side, so the axis of the workpiece 2 is inclined in the vertical plane as shown in Figure 3(b). However, since the two conveyor belts 3 are wrapped parallel to the guide grooves 13a and 14a of the two measuring pulleys 13 and 14 located on both sides of the measuring unit 5, the axis of the workpiece 2 in plan view is parallel to the conveyor belt 3 as shown in Figure 3(c). By projecting laser light 20 horizontally in the left-right direction from the light-emitting unit 17 to the light-receiving unit 18 of the measuring instrument 16 onto this workpiece 2, a two-dimensional side view image 21 including a silhouette image 25 of the workpiece 2 can be obtained.

[0032] Therefore, even if the workpiece 2 on the conveyor belt 3 is slightly tilted in the vertical direction, the measuring instrument 16 projects the workpiece 2 horizontally in the left-right direction, making it possible to accurately grasp the workpiece 2 as a workpiece image 25 projected from the side, regardless of the tilt of the workpiece 2 in the vertical direction, thereby preventing variations in the measurement accuracy of the outer diameter dimension X of the workpiece 2.

[0033] If the measurement is taken when workpiece 2 is approximately in the center of the projection area 19 as shown in Figure 5(b), the two-dimensional side image 21 projected onto the light-receiving unit 18 at that time will include not only the workpiece image 25 of workpiece 2 but also the belt image 26 of the conveyor belt 3, as shown in Figure 5(c). However, if the upper outline image 27 and lower outline image 28 of workpiece image 25 are separated vertically from the belt image 26, it is possible to distinguish the upper outline image 27 and lower outline image 28 of workpiece image 25 from the belt image 26.

[0034] Therefore, on the coordinate system of the two-dimensional side view image 21, the axis Y of the workpiece 2 on the coordinate system is determined from the data of the upper outline image 27 and lower outline image 28 of the workpiece image 25. The distance between the upper outline image 27 and the lower outline image 28 at the measurement position on this axis Y is then calculated, and this value is taken as the outer diameter dimension X of the workpiece 2 at the measurement position. This allows for accurate measurement of the outer diameter dimension X of the workpiece 2 without being affected by the orientation of the workpiece 2 in the vertical plane on the conveyor belt 3.

[0035] Furthermore, when calculating the outer diameter dimension X at one or more specific locations in the axial direction of workpiece 2, the axial position of workpiece 2 can be identified based on the images 27a, 27b of both ends of the upper outer shape image 27 and / or the images 28a, 28b of both ends of the lower outer diameter image 28, and the outer diameter dimension X corresponding to that position can be calculated. In addition, the image processing when calculating the outer diameter dimension X of workpiece 2 from the side two-dimensional image 21 may be performed by other methods.

[0036] The measuring instrument 16 only needs to view the workpiece 2 on the conveyor belt 3 from the left and right directions and extract a two-dimensional side image 21 of the workpiece 2 in the shape of its silhouette. Therefore, in addition to a projection type using laser light 20, an imaging type using a camera can also be employed.

[0037] Furthermore, the measuring instrument 16 is a left-right projection type and is equipped with a light-emitting unit 17 and a light-receiving unit 18 positioned on the left and right sides of the workpiece 2 on the conveyor belt 3. Compared to the case where the light-emitting unit 17 and light-receiving unit 18 are positioned above and below the conveyor belt 3, this reduces contamination of the light-emitting unit 17 and light-receiving unit 18, and has the advantage of reducing the need for cleaning and other maintenance.

[0038] The measurement result of the outer diameter dimension X of workpiece 2 is sent to the judgment unit. Workpieces 2 determined to be defective are then discharged onto the defective product discharge chute 30 by a compressed air type or pusher type discharge means 31 positioned on the opposite side of the defective product discharge chute 30 from the conveyor belt 3, and are discharged through the defective product discharge chute 30.

[0039] Workpieces 2 that are judged to be good are discharged to the good product discharge chute 32 by a discharge means 33, such as a compressed air type, located near the upstream of the good product discharge chute 32, and are discharged through the good product discharge chute 32. The measurement results of the measuring instrument 16 may be displayed as needed on a display device such as a personal computer or monitor, and the workpiece dimensions may also be judged as pass or fail based on the display. Furthermore, a dimensional correction command may be issued to the centerless grinding machine based on the dimensional measurement results of workpiece 2 to control the grinding dimensions.

[0040] Each component, such as the drive pulley 8, driven pulley 9, intermediate pulleys 11 and 12, measuring pulleys 13 and 14, drive motor 10, and measuring instrument 16, is mounted on a support frame 39 or the like.

[0041] This external shape measuring device 1 is used, for example, in combination with a centerless grinding machine. The workpiece 2, after infeed grinding from the centerless grinding machine, is fed onto the conveyor belt 3 via the input chute 4. The workpiece 2 on the conveyor belt 3 is supported from below by the two conveyor belts 3 and is continuously conveyed in the axial direction of the workpiece, passing through the deposit removal section 6 and the measuring section 5.

[0042] In the deposit removal section 6, air is blown onto the workpiece 2 from multiple air blowers 34 on both the upper and lower sides, removing coolant, dirt, and other contaminants adhering to the surface of the workpiece 2. The clean workpiece is then sent to the measurement section 5. The deposit removal section 6 has multiple air blowers 34, and the conveyor belt 3 is longer compared to the measurement section 5. However, as described later, the spacing F between the conveyor belts 3 is narrower in the deposit removal section 6, so there is no risk of the smaller diameter side of the workpiece 2 getting caught between the conveyor belts 3 and falling downwards while widening the gap between the conveyor belts 3, allowing the workpiece 2 to be conveyed smoothly. Furthermore, problems such as the smaller diameter side of the workpiece 2 getting caught between the conveyor belts 3 and damaging or cutting the conveyor belts 3 can be prevented.

[0043] In the measurement unit 5, the measuring instrument 16 measures the outer diameter dimension X of all workpieces 2 on the conveyor belt 3. As shown in Figure 4, the spacing D between the conveyor belts 3 in the measurement unit 5 is wide, so the lower outer shape 24 of the workpiece 2 in the measurement unit 5 extends downward by a dimension E from between the two conveyor belts 3. Therefore, in the measurement unit 5, the upper outer shape 23 of the workpiece 2 is located above the conveyor belt 3, while the lower outer shape 24 is located below the conveyor belt 3. When viewed from the side, the conveyor belt 3 does not overlap with the upper outer shape 23 and lower outer shape 24 of the workpiece 2, making it easy and reliable to grasp the upper outer shape image 27 and lower outer shape image 28 of the workpiece image 25, and enabling accurate measurement of the outer diameter dimension X of the workpiece 2.

[0044] By setting the spacing D between the conveyor belts 3 of the measuring unit 5 to a large value, the position of the workpiece 2 on the two conveyor belts 3 becomes relatively lower, causing the lower outer shape 24 of the workpiece 2 to protrude downward by a dimension E from between the two conveyor belts 3. Therefore, even when measuring by irradiating the laser beam 20 approximately horizontally in the left-right direction using the left-right projection type measuring instrument 16, the conveyor belts 3 do not overlap with the lower outer shape 24 of the workpiece 2, so the outer diameter dimension X of the workpiece 2 can be accurately measured without being affected by the two conveyor belts 3.

[0045] The spacing D between the conveyor belts 3 is determined by the spacing between the two guide grooves 13a and 14a of the measuring pulleys 13 and 14, and the measuring pulleys 13 and 14 are provided with guide grooves 13a and 14a at that spacing D.

[0046] In the deposit removal section 6 upstream of the measurement section 5, multiple air blowers 34 are provided on both the upper and lower sides to blow air onto the workpiece 2, which is being transported along the conveyor belt 3 in the direction of the workpiece axis, in order to remove coolant, debris, etc. By arranging multiple air blowers 34 in the deposit removal section 6 in this way and blowing air onto the workpiece 2 on the conveyor belt 3 from both the upper and lower sides, coolant, debris, etc. adhering to the workpiece 2 can be removed, thereby enabling accurate measurement of the outer diameter dimension X of the workpiece 2. The air discharge force of the air blowers 34 is set to an extent that does not affect the orientation of the workpiece 2 on the conveyor belt 3.

[0047] The deposit removal section 6 has a narrow parallel section 6A on the upstream side where the gap between the conveyor belts 3 in plan view is narrow and parallel, and a gradually widening section 6B where the gap in plan view gradually widens from the narrow parallel section 6A towards the measurement section 5. The gap F between the conveyor belts 3 in the narrow parallel section 6A is narrower than the gap D between the conveyor belts 3 in the measurement section 5.

[0048] For example, the guide grooves 9a, 11a, and 12a of the driven pulley 9 and the intermediate pulleys 11 and 12 are spaced F at a narrower interval than the spacing D between the conveyor belts 3 of the measuring section 5. Therefore, the spacing F between the conveyor belts 3 from the driven pulley 9 to the downstream intermediate pulley 12 is approximately constant. Because the workpiece 2 is supported and conveyed from below by the conveyor belts 3 with this narrow spacing F, problems such as the workpiece 2 falling downwards due to the widening of the spacing F between the two conveyor belts 3 caused by the workpiece 2's own weight, or damage to the conveyor belts 3 due to vibrations of the workpiece 2 that enter the space between the two conveyor belts 3, can be eliminated.

[0049] On the other hand, in the gradually widening section 6B, the spacing D of the guide grooves 13a of the measuring section pulley 13 is larger than the spacing F of the guide grooves 12a of the downstream intermediate pulley 12. Therefore, the distance between the two conveyor belts 3 between the downstream intermediate pulley 12 and the measuring section pulley 13 gradually widens from the intermediate pulley 12 side to the measuring section pulley 13 side. As a result, the workpiece 2 that has reached the downstream side of the deposit removal section 6 is conveyed to the measuring section 5 while gradually decreasing in height as the distance between the two conveyor belts 3 widens from F to D. Consequently, the workpiece 2 does not move rapidly up and down on the conveyor belt 3, and the workpiece 2 can be smoothly conveyed from the deposit removal section 6 to the measuring section 5 in a stable posture, preventing a decrease in measurement accuracy due to slight vertical vibrations of the workpiece 2.

[0050] Since the distance F between the two guide grooves 8a of the drive pulley 8 is gradually narrower than the distance D between the two guide grooves 13a and 14a of the measuring pulleys 13 and 14, the distance between the two conveyor belts 3 in the discharge section 7 between the downstream measuring pulley 14 and the drive pulley 8 gradually narrows from the measuring pulley 14 side to the drive pulley 8 side. Therefore, as the workpiece 2 that has passed through the measuring section 5 is gradually lifted as the distance between the two conveyor belts 3 narrows from D to F, it is conveyed downstream, and good workpieces 2 that have passed over the drive pulley 8 can be smoothly sent to the good workpiece discharge chute 32. Note that the distance between the guide grooves 8a of the drive pulley 8 may be the same as the distance between the guide grooves 9a of the driven pulley 9, etc., or it may be larger or smaller than the distance between the guide grooves 9a of the driven pulley 9, etc.

[0051] In this embodiment, the workpiece 2, after being infeed ground by a centerless grinding machine, is sorted into good and defective products after measuring its outer diameter X as follows. Specifically, the workpiece 2, after being infeed ground by a centerless grinding machine, is fed onto two conveyor belts 3 via an input chute 4. The workpieces on the two conveyor belts 3 are sequentially conveyed in the axial direction via a deposit removal unit 6 and a measuring unit 5. In the deposit removal unit 6, air is blown onto the workpiece 2 from both above and below to remove foreign matter such as coolant adhering to the workpiece 2. The distance between the two conveyor belts 3 in the deposit removal unit 6 is narrower from the driven pulley 9 to the intermediate pulley 12. Therefore, the workpiece 2 can be stably conveyed by the two conveyor belts 3.

[0052] In the measuring unit 5, the outer diameter X of the workpiece 2 is measured from a two-dimensional side image 21 obtained by projecting the workpiece 2 from the left and right directions using the measuring instrument 16 during transport. At this time, the spacing D between the two transport belts 3 in the measuring unit 5 is wider between the two measuring unit pulleys 13 and 14, and the lower outer diameter portion 24 of the workpiece 2 passing through the measuring unit 5 protrudes downward from the transport belt 3. Therefore, the workpiece image 25 can reliably capture the upper outer shape image 27 and lower outer shape image 28 corresponding to the upper outer shape portion 23 and lower outer shape portion 24 of the workpiece 2, and the outer diameter X of the workpiece 2 can be measured. Furthermore, since the outer diameter X of the workpiece 2 is measured from the two-dimensional side image 21 in the left and right directions captured by the measuring instrument 16, the outer diameter X of the workpiece 2 can be measured with high accuracy. After measurement, the workpiece 2 is judged as good or defective according to the measurement result, and good workpieces are discharged to the good product discharge chute 32, and defective workpieces are discharged to the defective product discharge chute 30.

[0053] In this way, the outer diameter dimension X of workpiece 2 can be measured continuously, and the outer diameter dimension X of workpiece 2 can be measured with high precision without being affected by the orientation of workpiece 2 in the vertical plane. Furthermore, 100% measurement is possible, and real-time equipment control (grinding dimension control) is possible, which helps to stabilize quality. In addition, since the measurement of all workpieces 2 can be recorded, sign management is possible, which is useful for traceability. The cycle time for outer diameter measurement is also shortened. It can also easily handle the measurement of the outer diameter of workpieces 2 that are being continuously transported.

[0054] In this embodiment, after capturing a two-dimensional side view image 21 of the workpiece 2 with the measuring instrument 16, the outer diameter dimension calculation unit 22 calculates the outer diameter dimension X of the workpiece 2 from the two-dimensional side view image 21. However, as shown by the dashed line in Figure 2, an outer shape calculation unit 40 may be provided instead of the outer diameter dimension calculation unit 22 to calculate the tapered shape and other outer shapes of the workpiece 2 from the two-dimensional side view image 21 and to determine the quality of the outer shape. Furthermore, by using both the outer diameter dimension calculation unit 22 and the outer shape calculation unit 40, it is also possible to calculate both the outer diameter dimension X and the outer shape of the workpiece 2.

[0055] As shown in Figure 5(c), in the case of a two-dimensional side view image 21 having an upper outer shape image 27 including end-end images 27a, 27b and upper side image 27c corresponding to each part of the upper outer shape 23 of the workpiece 2, and a lower outer shape image 28 including end-end images 28a, 28b and lower side image 28c corresponding to each part of the lower outer shape 24 of the workpiece 2, the outer shape calculation unit 40 can calculate the taper angle of the workpiece 2 by combining the upper side image 27c and the lower side image 28c, and can also calculate the overall length in the axial direction of the workpiece 2 by combining the end-end images 27a, 27b and end-end images 28a, 28b. Thus, not only the overall outer shape and dimensions of the workpiece 2 can be calculated, but also the partial outer shape and dimensions of any opposing points on the two-dimensional side view image 21 of the workpiece 2.

[0056] For example, if workpiece 2 has a stepped section and a circumferential groove in the middle of its axial direction, it is possible to calculate not only the overall external shape of workpiece 2, but also the positions of the stepped section and circumferential groove. Furthermore, if workpiece 2 has R-shaped sections at both ends, the stepped section, the circumferential groove, etc., it is possible to calculate not only the overall external shape of workpiece 2, but also the position of the R-shaped sections and the overall shape including the R-diameter.

[0057] Therefore, by combining the upper outline image 27 and the lower outline image 28 of the necessary parts of workpiece 2, it is possible to arbitrarily determine the outer shape of workpiece 2 from the projected image, which is the side two-dimensional image 21.

[0058] Furthermore, the workpiece 2 to be measured for the outer diameter dimension X and the workpiece 2 to be used for calculating the outer shape are not limited to the tapered shaft shown in Figure 3, but include various types as shown in Figures 6(a) to (d). Figure 6(a) shows a small-diameter straight shaft 35 having a straight section 35b and a tapered section 35c on both sides in the axial direction, flanking a circumferential groove 35a. In such a straight shaft 35, the straight section 35b and the tapered section 35c can also be used as the measurement target areas.

[0059] Figure 6(b) shows a flanged shaft 36, which has a stepped portion 36c between a large diameter portion 36a and a small diameter portion 36b, and a flange portion 36d on the side of the large diameter portion 36a opposite to the small diameter portion 36b. In such a flanged shaft 36, the large diameter portion 36a and the small diameter portion 36b may be the measurement target areas. Figure 6(c) shows a stepped shaft 37, which has a stepped portion 37c between a large diameter portion 37a and a small diameter portion 37b. In such a stepped shaft 37, the large diameter portion 37a and the small diameter portion 37b may be the measurement target areas. Figure 6(d) shows a tapered roller 38, which has tapered portions 38b and 38c on both sides of a straight portion 38a. In such a tapered roller 38, the straight portion 38a and the tapered portions 38b and 38c may be the measurement target areas.

[0060] When measuring these workpieces 2, the projected shape of the workpiece 2 can be grasped by a two-dimensional side view image 21 that includes an upper outer shape image 27 of the upper outer shape portion 23 and a lower outer shape image 28 of the lower outer shape portion 24 at the measurement site of the workpiece 2.

[0061] Although the embodiments of the present invention have been illustrated above, the present invention is not limited to these embodiments, and various modifications are possible without departing from the spirit of the invention. The workpiece 2 only needs to have a circular outer surface of the part to be measured. For example, the part to be measured may be a straight cylinder, a straight cylindrical shape, a tapered cylinder, a tapered cylindrical shape, or the like.

[0062] Even when measuring the outer diameter dimension X of a workpiece 2 after it has been machined, the machine used does not have to be a centerless grinding machine. Furthermore, the workpiece 2 whose outer diameter dimension X is to be measured is not limited to a machined workpiece 2 discharged from a machine. For example, it may be used when matching workpieces 2 upstream of an assembly machine. In that case, a discharge mechanism should be provided to sort the workpieces 2 into predetermined dimensional ranges after measurement.

[0063] When measuring the outer diameter dimension X of the workpiece 2 using the measuring instrument 16, the outer diameter dimension X of one or more measurement points of the workpiece 2 may be calculated based on a two-dimensional side image 21 of the workpiece 2 when one or more measurement points of the workpiece 2 enter the measurement area of ​​the measuring instrument 16. Alternatively, a two-dimensional side image 21 may be obtained each time multiple measurement points of the workpiece 2 pass through the projection area 19 of the measuring instrument 16, and the average value or representative value of the outer diameter dimension X calculated for each of these multiple two-dimensional side images 21 may be used as the measurement value of that measurement point. For example, when measuring the outer diameter dimension X of a straight section of workpiece 2, once workpiece 2 is detected by the passage confirmation sensor 29, n measurements may be taken at predetermined time intervals t (e.g., 0.1 seconds) from that point, and the average value or representative value of those n measurements may be used as the measurement value of workpiece 2.

[0064] The conveyor belt 3 may be made of untwisted wire material with a circular cross-section, or it may be made of twisted wire material made by twisting multiple wire materials together to form a circular cross-section. In addition to wire material, it is also possible to use untwisted wire material or twisted wire material made of resin. A circular cross-section is preferable for the conveyor belt 3, but a polygonal cross-section close to a circular cross-section is also acceptable.

[0065] In the adhering material removal section 6, it is desirable to transport the workpiece 2 using two conveyor belts 3. However, if the workpiece 2 is prone to falling off the conveyor belts 3, guide members may be provided to guide the workpiece 2 on the two conveyor belts 3 from both the left and right sides, thereby preventing the workpiece 2 from falling. Furthermore, if the workpiece 2 has a large outer diameter and is heavy, and it is difficult to discharge the workpiece 2 from the conveyor belts 3 to the defective product discharge chute 30 by simply blowing compressed air from the side, a pulley with a narrow gap between guide grooves may be placed upstream of the defective product discharge chute 30 to narrow the gap between the two conveyor belts 3.

[0066] The projection area (measurement area) 19 of the measuring instrument 16 is preferably circular, but even if there is variation in the orientation of the workpiece 2, it is sufficient as long as the measurement area falls within the projection area 19. For example, the measuring instrument 16 may have a rectangular projection area 19. In addition to a measuring instrument 16 equipped with a laser beam emitter 17 and a light receiver 18, an imaging type such as a camera can also be used as long as it can capture the side shape of the workpiece 2 in two dimensions. [Explanation of symbols]

[0067] 1 External shape measuring device 2 Work 3. Conveyor belt 4 Shots to be taken 5 Measuring part 6 Deposit removal section 7 Discharge section 8 Drive pulley 9 Driven pulley 10 Drive motor 11,12 Intermediate pulley 13,14 Measuring pulley Guide grooves 8a, 9a, 11a~14a 16 Measuring instruments 17. Lighting Unit 18 Light receiving part 21 Side view two-dimensional image 22 Outer diameter dimension calculation section 25 Work Images 26 Belt Images 23 Upper outline part 24 Lower outer shape portion 27 Upper outer shape image 28 Lower outer shape image 40 Outer shape calculation unit

Claims

1. In a workpiece outer shape measuring device, the workpiece is supported from below by two conveyor belts and conveyed in the axial direction while the outer shape of the workpiece is measured by a measuring instrument, The measuring instrument captures the workpiece, including its upper and lower outer shapes, as a two-dimensional side view image from a direction substantially perpendicular to the axial direction of the workpiece on the conveyor belt, The conveyor belt of the measuring section on which the measuring instrument is positioned has an upper outer shape and a lower outer shape that protrude from both the upper and lower sides of the conveyor belt. At least the conveyor belt upstream of the measuring unit has a narrower spacing than the spacing between the conveyor belts of the measuring unit. A workpiece outer shape measuring device characterized by the following features.

2. The aforementioned two-dimensional side view image includes an upper outer shape image of the upper outer shape portion extending from both ends in the axial direction of the workpiece to the upper portion, and a lower outer shape image of the lower outer shape portion extending from both ends in the axial direction of the workpiece to the lower portion. The external shape measuring device for a workpiece according to feature 1.

3. The system includes an external shape calculation unit that calculates the external shape of the workpiece, including the upper and lower external shapes, from the aforementioned two-dimensional side view image. The external shape measuring device for a workpiece according to claim 1 or 2.

4. It has an outer diameter dimension calculation unit that calculates the outer diameter dimension between the upper outer shape portion and the lower outer shape portion of the workpiece from the aforementioned two-dimensional side view image. The external shape measuring device for a workpiece according to claim 1 or 2.

5. Upstream of the measuring unit, there is a deposit removal unit for removing deposits from the workpiece during transport. The conveyor belt of the deposit removal unit has a narrower spacing than the wider spacing between the conveyor belts of the measuring unit. The external shape measuring device for a workpiece according to feature 1.

6. The distance between the conveyor belts on the measuring section side of the deposit removal section is The gap gradually widens from the narrow gap to the wider gap of the measuring section. The distance between the conveyor belts downstream of the measuring unit is gradually increased from the wide distance of the measuring unit. It gets narrower The external shape measuring device for a workpiece according to feature 5.

7. At least the outer peripheral contact portion of the workpiece that contacts the conveyor belt is concentric with respect to the axis of the workpiece. The external shape measuring device for a workpiece according to feature 1.

Images