Method for measuring minimum clearance of spiral spring

Abstract

A method for measuring the minimum clearance of a spiral spring, comprising: first, determining an attitude coordinate system of a spiral spring (8); on this basis, implementing radial segmentation of an edge image by means of preset cutting lines, the edge image that has been subjected to the radial segmentation being a set of arc line segments arranged at intervals; calibrating each pair of arc line segments on two sides of a clearance one by one; then calculating the distances between discrete points on each pair of calibrated arc line segments; and comparing the distance values with a preset value, so as to accurately determine whether the clearance of the spiral spring (8) is qualified.

Description

A method for detecting the minimum clearance of a scroll spring Technical Field

[0001] The present invention relates to the technical field of spiral spring size detection, and in particular to a method for detecting a minimum gap of a spiral spring. Background Art

[0002] When used in the phase adjuster of an automobile engine, a scroll spring can control the opening and closing timing of the valve according to the engine speed, achieving complete combustion of gasoline, thereby improving fuel economy and environmental performance. This places extremely high demands on the structural response of the spring component. The minimum clearance of the scroll spring is an indicator of whether the scroll spring is qualified.

[0003] The method for detecting the minimum gap of an object using a visual inspection system is to extract the edges on both sides of the gap and set discrete points on both edges. The minimum distance between the discrete points on both sides is calculated to obtain the minimum value, thereby determining the minimum gap. The difficulty in detecting the gap of a spiral spring lies in the fact that the spiral spring has the characteristic of being continuously wound as a whole and radially superimposed as a whole. That is, the gap and the spring body are in a continuous winding and stacked form as a whole, with no boundary features between the layers. Therefore, there are at least the following problems: First, the discrete points on one side of the gap will be used to calculate the distance with the discrete points in other layers, wasting computing power; second, the thickness of the spring body is difficult to distinguish from the gap between the springs, that is, it is difficult to determine whether the calculated minimum distance is the thickness of the spring.

[0004] Summary of the Invention

[0005] In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a method for detecting the minimum gap of a scroll spring, which can accurately determine whether the minimum gap of the scroll spring is qualified.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A method for detecting the minimum gap of a scroll spring, the detection method comprising the following steps:

[0008] Step S1: collecting an image of the top surface of the scroll spring and extracting the image edge; the extracted image edge corresponds to the edge of the scroll spring;

[0009] Step S2: Determine the posture coordinate system of the scroll spring and parameterize the image edge in the posture coordinate system; wherein determining the posture coordinate system of the scroll spring includes the following steps S2.1 and S2.2:

[0010] Step S2.1: Identify and locate the image features corresponding to the first hook and the second hook from the image; since the shapes of the first hook and the second hook are stable and have great differences relative to the spiral spring body, they are easy to identify and locate from the image.

[0011] Step S2.2: extracting a feature point A and a feature point B from the image feature area of ​​the first hook and the second hook, respectively, and aligning the line segments where the two feature points are located with the posture coordinate axis and the posture coordinate origin;

[0012] Step S3: setting a dividing line in the attitude coordinate system, wherein the dividing line divides the image edge into at least two areas, and the dividing line radially passes through the scroll spring. At this time, the image edge of each divided area is a group of arc segments arranged at intervals;

[0013] Step S4: calibrating each pair of adjacent arc segments corresponding to the scroll spring gap; specifically, first removing the image edges corresponding to the first hook portion and the second hook portion, then excluding the outermost and innermost arc segments, and then sequentially calibrating the arc segments adjacent to each other in the radial direction as the arc segments corresponding to the scroll spring gap;

[0014] Step S5: taking a set of discrete points on the calibrated arc segment, and calculating the distance between each discrete point on the calibrated arc segment and each discrete point on the corresponding arc segment;

[0015] Step S6: If the calculated spacing between the discrete points is smaller than the preset value, the size is judged to be unqualified; otherwise, it is judged to be qualified.

[0016] The above method first determines the scroll spring's posture coordinate system. Based on this, it can achieve radial segmentation of the edge image using preset cutting lines. The edge image after radial segmentation is a set of arc segments set at intervals. By calibrating each pair of arc segments on both sides of the gap one by one, and then calculating the distance between the discrete points of each calibrated pair of arc segments, and comparing the distance value with the preset value, it can accurately determine whether the scroll spring gap is qualified.

[0017] Furthermore, in the method for detecting the minimum gap of a scroll spring, in step S2.2, the posture coordinate system is a rectangular coordinate system, the line connecting the feature points is the x-axis, and the direction from A to B is the positive direction.

[0018] Furthermore, in the method for detecting the minimum gap of a spiral spring, in step S2.2, the characteristic points A and B are the centers of the inscribed fitting circles of the first hook and the second hook, respectively. As a preferred solution of this application, generally, using the endpoint positions of the first hook and the second hook as characteristic points will cause the posture coordinate system generated by each spiral spring to deviate greatly from the actual posture of the spiral spring due to the deviation of the endpoint positions of each spiral spring. In this application, since the overall positions of the first hook and the second hook are relatively stable with the spiral spring body, using the centers of the inscribed fitting circles of the first hook and the second hook as characteristic points can ensure that the posture coordinate system generated by each spiral spring is relatively stable. This facilitates reducing the actual calculated segmentation area according to the actual spring characteristics and saves computing power.

[0019] Furthermore, the method for detecting the minimum gap of a scroll spring comprises determining the scroll spring's posture coordinate system and then calibrating a characteristic point C corresponding to the location of the scroll spring's inner hole. The method for extracting discrete points in step S5 is as follows: each arc segment's endpoint is connected to the characteristic point C to form an angle, and a set of rays passing through the characteristic point C are arranged at equal intervals between the angles. The intersection of the rays and the arcs is the discrete point of the arc segment. As a preferred solution of this application, this method ensures uniformity in the extraction of discrete points, thereby ensuring detection accuracy.

[0020] Furthermore, in the method for detecting the minimum gap of a spiral spring, step S6 further includes the following steps: step S6.1: comparing the spacing between discrete points to obtain the minimum spacing value, and calibrating a pair of discrete points corresponding to the minimum spacing value; if the spacing between the pair of discrete points is greater than a preset value, executing step S6.2; step S6.2: intercepting the pair of arc segment areas where the pair of discrete points calibrated in step S6.1 are located, re-taking a more dense set of discrete points for the intercepted pair of arc segments, calculating the spacing between each discrete point on the intercepted arc segment and each discrete point on the corresponding arc segment; comparing the obtained spacing with the preset value again to determine whether the size is qualified. Based on the above method, the detection accuracy can be improved.

[0021] It can be seen from the above technical solution that the present invention has the following beneficial effects:

[0022] 1. The present invention provides a method for detecting the minimum gap of a scroll spring. The method first determines the scroll spring's posture coordinate system. Based on this, the edge image is radially segmented using a preset cutting line. The segmented edge image is then represented by a set of spaced arc segments. Each pair of arc segments on either side of the gap is calibrated one by one, and the distance between discrete points in each calibrated pair of arc segments is calculated. The distance value is then compared with a preset value. This method can accurately determine whether the scroll spring gap is acceptable.

[0023] 2. This invention provides a method for detecting the minimum gap of a scroll spring. This method uses the centers of the inscribed fitting circles of the first and second hooks as feature points to generate posture coordinates. This ensures a relatively stable posture coordinate system for each scroll spring. This facilitates narrowing the actual calculation segmentation area based on the actual spring characteristics, saving computing power. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a scroll spring size detection device according to an embodiment of the present application;

[0025] FIG2 is a schematic structural diagram of a material lateral dimension detection device according to Example 1 of the present application;

[0026] FIG3 is a schematic structural diagram of a material lateral dimension detection device according to Example 2 of the present application;

[0027] FIG4 is a schematic structural diagram of a material lateral dimension detection device in a reset state according to Example 2 of the present application;

[0028] FIG5 is an exploded view of the components of the detection device and the driving device described in Example 2 of the present application;

[0029] FIG6 is a schematic structural diagram of the frame in Example 2 of the present application;

[0030] FIG7 is a schematic structural diagram of the detection device in FIG4 in a state of moving to the left;

[0031] FIG8 is a schematic diagram of the detection device in FIG4 being moved to the first waste discharge position;

[0032] FIG9 is a plan view of the scroll spring described in Examples 3 and 4 of the present application;

[0033] FIG10 is a schematic diagram of step S2 in a method for detecting a minimum gap of a scroll spring according to Example 4 of the present application;

[0034] FIG11 is a schematic diagram of step S3 in a method for detecting a minimum gap of a scroll spring according to Example 4 of the present application;

[0035] FIG12 is a schematic diagram of step S4 in a method for detecting a minimum gap of a scroll spring according to Example 4 of the present application;

[0036] FIG13 is a schematic diagram of step S5 in a method for detecting the minimum gap of a scroll spring according to Example 4 of the present application.

[0037] In the figure: 1-feeding channel; 11-distributing platform; 12-second waste material outlet; 13-second conveying device;

[0038] 2-Feeding device;

[0039] 3-guide slide;

[0040] 4 - Detection device; 40 - Detection compartment; 41 - First clamp; 411 - Limiting frame; 4111 - Pull plate; 412 - Slide groove; 42 - Second clamp; 43 - Inductive sensor; 44 - Limiting clamp; 441 - Base; 442 - Clamp; 443 - Slide rod; 4431 - Limiting protrusion; 444 - Compression spring; 445 - Guide column; 45 - Spacer; 46 - Clutch mechanism; 461 - Return spring; 462 - Rocker; 463 - Second limiting member; 4631 - Pressure wheel;

[0041] 5-driving assembly; 51-first driving cylinder; 52-second driving cylinder; 53-third driving cylinder; 54-fourth driving cylinder; 541-push plate; 542-push block;

[0042] 6-frame; 61-slide rail; 62-vertical plate; 621-first stopper;

[0043] 7- visual inspection station; 71- first inspection station;

[0044] 8-volute spring; 81-first hook; 82-second hook. DETAILED DESCRIPTION

[0045] Example 1

[0046] During the automated production process, it is usually necessary to measure the dimensions of the product in order to eliminate products with unqualified dimensions. The lateral dimensions of the material can be measured directly by a distance sensor, but if the material being tested has hollow features in the measurement direction, the distance sensor cannot be used for direct measurement if the material posture is not accurately positioned. Traditional automated testing equipment also uses a method of pressing a plate down on the material to calculate the thickness of the material based on the pressing stroke of the plate. The limitation of this method is that it is not suitable for situations where the material being tested has elasticity on the side. The above two methods of measuring dimensions are particularly unsuitable for detecting the thickness of spiral springs. When the spiral spring is placed horizontally, it has hollow features in the vertical direction and is not suitable for direct measurement by a distance sensor. In addition, the excess thickness of the spiral spring is caused by the fact that the coils of the spring are not completely in the same height plane. The method of pressing the plate down to position it will cause it to deform in the thickness direction, resulting in inaccurate measurement results.

[0047] In combination with the material lateral dimension detection device shown in Figures 1 and 2, it is used to detect whether the lateral dimension of the material to be detected is qualified, including:

[0048] A feeding device 2 is provided with a guide slide 3 at the front end of the feeding direction of the feeding device 2, and the feeding device 2 is used to horizontally transport the material to be detected to the guide slide 3, and the guide slide 3 is used to guide the material to be detected to slide in its lateral direction; a detection device 4, the detection device 4 includes a first clamping plate 41 and a second clamping plate 42, and a detection cavity 40 is provided between the first clamping plate 41 and the second clamping plate 42, and the spacing of the detection cavity 40 is adapted to the lateral qualified size of the material to be detected; the detection device 4 also includes a control system and an inductive sensor 43 connected to the control system for communication, and the inductive sensor 4 3 is arranged on one side of the discharge port of the detection chamber 40; the induction sensor 43 is used to detect whether the material to be detected falls out of the discharge port of the detection chamber 40 within a preset timing time, so as to determine whether its lateral size is qualified; and also includes a driving component 5, the driving component 5 is transmission-connected to the first clamping plate 41 and the second clamping plate 42. When the detection device 4 determines that the size of the material to be detected exceeds the preset value, the driving component 5 is used to drive the first clamping plate 41 and the second clamping plate 42 to move to the first discharge position, and drive the first clamping plate 41 and the second clamping plate 42 to move relatively away from each other, so as to separate and transfer the material whose size exceeds the preset value.

[0049] Based on the above structure, the principle of the scroll spring size detection device is as follows: the control system has a built-in timer. When the feeding device 2 pushes the material to be detected to the guide chute 3, the timer starts timing. If the induction sensor 43 detects that the material to be detected falls out of the discharge port of the detection cavity 40 within the preset timing time, it is judged that the lateral size of the material is qualified. Otherwise, the material is stuck in the detection cavity 40, and the size is judged to exceed the preset value. It should be noted that the spacing between the detection cavities 40 and the qualified lateral size of the material to be detected are loosely matched. If the lateral size of the material to be detected exceeds the range, the material to be detected and the detection cavity 40 are tightly matched, which will cause the material to be detected to be stuck in the detection cavity 40 and unable to fall out.

[0050] Specifically, a sensor may be provided at the entrance of the guide slide 3 to trigger the start of the timing, or the start time of the feeding device 2 may be directly used as the start time of the timing.

[0051] It should be noted that when the material to be detected falls out of the discharge port of the detection chamber 40, it should be understood that the material to be detected has completely passed through the sensing area of ​​the inductive sensor 43, that is, the inductive sensor 43 needs to detect the change from "no" to "yes" and then to "no" within the preset timing time. If the front end of the material to be detected falls out of the detection chamber 40 and the rear end is stuck in the detection chamber 40, at this time, although the position of the inductive sensor 43 has detected the material to be detected, it has only detected the change from "no" to "yes", so it is still judged that the material size exceeds the preset value. It should be noted that if the upper limit of the size of the material to be detected completely exceeds the outlet size of the detection chamber 40, the inlet size of the detection chamber 40 needs to be increased, that is, the interval size of the detection chamber 40 is wide at the inlet and narrow at the outlet, and the outlet size of the detection chamber 40 is adapted to the lateral qualified size of the material to be detected to ensure that the material to be detected can enter the detection chamber 40, and the material with a size exceeding the preset value is transferred by the drive component 5.

[0052] As shown in Figure 2 , in this embodiment, a spacer 45 is provided between the first and second plates 41, 42. When the first and second plates 41, 42 are attached to the spacer 45, the detection compartment 40 conforms to the qualified dimensions of the material to be detected. The spacer 45 is used to limit the relative position between the first and second plates 41, 42 in the reset state. Specifically, the spacer 45 is mounted on the first plate 41, and in the reset state, the second plate 42 is pressed against the spacer 45.

[0053] This embodiment further includes a frame 6, which is provided with slide rails 61. The first and second clamping plates 41, 42 are slidably mounted on the slide rails 61. Specifically, the slide rails 61 are guide rods that pass through the first and second clamping plates 41, 42. There are four slide rails 61, and linear bearings are provided on the first and second clamping plates 41, 42, corresponding to the slide rails 61. The frame 6 also includes a pair of vertical plates 62. The ends of the slide rails 61 are mounted on the pair of vertical plates 62, with the first and second clamping plates 41, 42 positioned between the pair of vertical plates 62.

[0054] In this embodiment, the slide cavity of the guide drop chute 3 is an inverted cone, with its outlet adapted to the lateral dimensions of the material to be inspected. After being pushed horizontally into the guide drop chute 3, the material to be inspected is restrained by the slide cavity of the guide drop chute 3, allowing it to fall directly into the inspection compartment 40 after exiting the guide drop chute 3. Specifically, the material to be inspected falls vertically out of the guide drop chute 3 and into the inspection compartment 40. In this embodiment, the inspection compartment 40 extends vertically.

[0055] As shown in FIG2 , in this embodiment, a position-limiting clamp 44 is provided at the outlet of the detection compartment 40. The position-limiting clamp 44 is disposed on the first clamping plate 41 or the second clamping plate 42 and is in driving connection with the drive assembly 5. When the detection device 4 determines that the size of the material to be detected exceeds a preset value, the drive assembly 5 drives the position-limiting clamp 44 to move to the outlet of the detection compartment 40. The position-limiting clamp 44 is used to limit the material to prevent it from falling out during the transfer process if it fails to move to the first discharge position.

[0056] As shown in Figure 2, in this embodiment, the driving assembly 5 includes a first driving cylinder 51, a second driving cylinder 52 and a third driving cylinder 53 that are respectively connected to the first clamping plate 41, the second clamping plate 42 and the limit clamp 44. The first driving cylinder 51 is used to drive the first clamping plate 41 and push the second clamping plate 42 to move to the first discharging position. The second driving cylinder 52 is used to adjust the distance between the first clamping plate 41 and the second clamping plate 42 to achieve the relative opening and closing of the first clamping plate 41 and the second clamping plate 42. The third driving cylinder 53 is used to drive the limit clamp 44 to move to the exit position of the detection compartment 40. In the reset state, the third drive cylinder 53 resets the limit card 44 to the outside of the exit position of the detection chamber 40, the second drive cylinder 52 resets the second clamping plate 42 to the distance between it and the first clamping plate 41 and the lateral size of the material to be detected (in the closed state), and the first drive cylinder 51 resets the first clamping plate 41 to the detection chamber 40 on the corresponding exit side of the guide slide 3; when the detection device 4 determines that the size of the material to be detected exceeds the preset value, the third drive cylinder 53 first drives the limit card 44 to move to the position blocking the exit of the detection chamber 40, and then pushes the first clamping plate 41 and the second clamping plate 42 to move as a whole to the first discharging position through the first drive cylinder 51, and finally the third drive cylinder 53 drives the limit card 44 to reset, and the second drive cylinder 52 drives the second clamping plate 42 to move away from the first clamping plate 41, and the material falls out of the detection chamber 40. In this embodiment, the third drive cylinder 53 fixing assembly is installed on the first clamping plate 41, the limit clamp 44 is slidably set on the first clamping plate 41, and the second clamping plate 42 extends to the opposite side of the limit clamp 44. If the material to be inspected moves to the position of the limit clamp 44 and is stuck, the limit clamp 44 can clamp the material to be inspected on the second clamping plate 42.

[0057] Example 2

[0058] This embodiment is a replacement for the drive assembly 5 based on the embodiment 1.

[0059] As shown in Figures 3 to 5, specifically, in this embodiment, the driving assembly 5 includes a fourth driving cylinder 54, and a push plate 541 is provided on the telescopic assembly of the fourth driving cylinder 54, and the push plate 541 is provided with a push block 542; the first splint 41 is installed on the side away from the second splint 42 of the second splint 41, and the push plate 541 is provided with a push block 542; the first splint 41 is installed on the side away from the second splint 42 of the second splint 41, and the limit frame 411 includes a pull plate 4111, and the pull plate 4111 is spaced apart from the first splint 41, and the push block 542 is provided between the pull plate 4111 and the first splint 41; the limit clamping member 44 includes a seat body 441, and the seat body 441 is provided with a clamping head 442 on the side of the seat body 441 near the first splint 41, and the seat body 441 is provided with a sliding rod 443 on the side away from the first splint 41, and the push plate 541 is slidably arranged on the sliding rod 443 Correspondingly, the push plate 541 is provided with a through hole adapted to the slide rod 443, a compression spring 444 is provided between the seat body 441 and the push plate 541, and a limiting convex portion 4431 is provided on the slide rod 443 corresponding to the outer side of the push plate 541; specifically, the compression spring 444 is sleeved on the slide rod 443; the limiting convex portion 4431 is a nut threadedly connected to the slide rod 443; when the push block 542 moves to fit with the first splint 41, the The clamping head 442 is at the lower end of the discharge port of the detection cavity 40; when the push block 542 moves to fit with the pull plate 4111, the clamping head 442 is outside the discharge port of the detection cavity 40; it also includes a fixed first limit member 621. When the fourth drive cylinder 54 pushes the first clamping plate 41 and the second clamping plate 42 to move as a whole to the first discharge position, the first limit member 621 is used to push the seat body 441 to move until the clamping head 442 is outside the detection cavity 40.

[0060] When the cam 42 is in the open position, the first stop 41 is engaged with the second stop 42, and the second stop 42 is in the open position. When resetting from the first discharge position, the push plate 541 moves in the opposite direction until the push block 542 is in contact with the pull plate 4111. The pull plate 4111 pulls the first and second clamping plates 41, 42 to move and reset as a whole. During this process, the compression spring 444 and the limiting protrusion 4431 act on the push plate 541, causing the limiting clamp 44 to automatically return to its reset state. Specifically, a limiting block is provided on the vertical plate 62, corresponding to the side of the first clamping plate 41 away from the second clamping plate 42, for limiting the reset position of the first clamping plate 41. Based on the above device, compared to using two drive cylinders to drive the first clamping plate 41 and the limiting clamp 44 separately, the present application achieves the same effect through a single drive device, and has the advantages of low manufacturing cost, simple control, and good reliability.

[0061] As shown in Figure 5 , in this embodiment, the clamping head 442 is positioned at the center of the base 441. A pair of guide posts 445 are provided on the base 441, corresponding to either side of the clamping head 442. The first and second clamping plates 41 and 42 are provided with guide holes corresponding to the guide posts 445, which slide within the guide holes. The first stopper 621 is a push rod corresponding to the pair of guide posts 445. This ensures the stability of the movement of the stopper 44. Furthermore, the stopper frame 411 also includes a pair of guide rods positioned between the pull plate 4111 and the first clamping plate 41. The push block 542 slides on the guide rods. The push block 542 and the push plate 541 are secured by a connecting rod that passes through the pull plate 4111. Furthermore, the telescopic rod of the fourth drive cylinder 54 is mounted at the center of the push plate 541. The sliding rod 443 and the connecting rod are symmetrically positioned on either side of the telescopic rod of the fourth drive cylinder 54. This enhances movement stability.

[0062] As shown in Figures 4 and 5 , this embodiment further includes a clutch mechanism 46, which includes a return spring 461 connected to the second clamping plate 42 and configured to press the second clamping plate 42 toward the first clamping plate 41. The clutch mechanism 46 also includes a rocker arm 462, which is rotatably connected to the second clamping plate 42 and slidably connected to the first clamping plate 41 at one end of the rocker arm 462 away from the second clamping plate 42. The clutch mechanism 46 also includes a fixed second stopper 463. When the fourth drive cylinder 54 drives the first and second clamping plates 41 and 42 to move as a whole to the first discharge position, the second stopper 463 can push the rocker arm 462 to rotate until the distance between the first and second clamping plates 41 and 42 is increased. In this embodiment, a vertically extending chute 412 is provided on the first clamping plate 41, and a pulley disposed within the chute 412 is provided at a corresponding position of the rocker arm 462, which is rotatably connected to the second clamping plate 42. It should be noted that the extension trajectory of the slideway 412 cannot be parallel to the movement direction of the first clamping plate 41. The second stopper 463 is mounted on the frame 6. A pressure wheel 4631 is provided at the front end of the second stopper 463, which abuts against the side of the rocker 462 via the pressure wheel 4631. Specifically, the return spring 461 is a compression spring, disposed between the vertical plate 62 and the second clamping plate 42. The rocker 462 and the second stopper 463 are disposed in pairs on either side of the first clamping plate 41 and the second clamping plate 42.

[0063] Based on the above device, in the reset state, as shown in Figure 4 , due to the action of the reset spring 461, the second clamping plate 42 is aligned with the first clamping plate 41, the rocker arm 462 is tilted as a whole, and the second stopper 463 is positioned at the front end of the rocker arm 462 in the direction of movement toward the first discharge position. As shown in Figure 8 , during the process of the fourth drive cylinder 54 driving the first and second clamping plates 41, 42 to move toward the first discharge position, the rocker arm 462, restrained by the second stopper 463, swings, thereby pushing the second clamping plate 42 open, allowing the material to automatically fall out of the detection compartment 40 once in place. Compared to using an additional cylinder to drive the second clamping plate 42 to engage or disengage, the above device offers the advantages of simpler control and greater stability.

[0064] In this embodiment, the pivot connection point of the swing rod 462 is above the sliding track of the swing rod 462. This ensures that when the swing rod 462 moves in the reset direction, the force exerted by the reset spring 461 on the sliding contact point of the swing rod 462 has a downward component, thereby ensuring that the sliding end of the swing rod 462 is reset and preventing the swing rod 462 from moving horizontally and getting stuck, which would prevent the second clamping plate 42 from being reset toward the first clamping plate 41.

[0065] Example 3

[0066] As shown in FIG1 , a scroll spring size detection device includes a scroll spring size detection device as described in Example 1 or 2. It also includes:

[0067] The feeding channel 1 is provided with a distribution platform 11 at the front end of the feeding direction of the feeding channel 1, and a lifting device is provided on the distribution platform 11. After the material at the front end of the feeding channel 1 is transported to the distribution platform 11, the distribution platform 11 is lifted by the lifting device to achieve isolation of the material at the front end and the material at the rear side.

[0068] The machine also includes a visual inspection station 7, which is used to detect whether the forward dimension of the scroll spring is qualified. The visual inspection station 7 includes a first inspection station 71, which is arranged on one side of the material distribution platform 11. The guide drop chute 3 is arranged on the side of the first inspection station 71 away from the material distribution platform 11. The feeding device 2 is a driving cylinder, and the feeding device 2 is also used to push the scroll spring from the material distribution platform 11 to the first inspection station 71. If the first inspection station 71 determines that the material to be inspected is qualified, the feeding device 2 continues to push the material to be inspected to the guide drop chute 3.

[0069] It also includes a second waste outlet 12 and a second conveying device 13. The second waste outlet 12 is arranged on one side of the first detection station 71. The second conveying device 13 is used to convey materials whose sizes are judged by the first detection station 71 to exceed the preset value to the second waste outlet 12.

[0070] Based on the above device, the forward and lateral dimensions of the spiral spring can be detected by a single device, thereby improving the detection efficiency.

[0071] Example 4

[0072] On the basis of Example 3, the first detection station 71 is used to detect whether the minimum gap of the spiral spring 8 is qualified.

[0073] In this regard, this embodiment provides a method for detecting the minimum gap of a spiral spring. As shown in FIG9 , the inner end and the outer end of the spiral spring 8 are respectively provided with a first hook 81 and a second hook 82 .

[0074] When used in a vehicle engine's phase adjuster, a scroll spring should be able to control the timing of valve opening and closing according to engine speed, ensuring full combustion of gasoline and improving fuel economy and environmental performance. This places extremely high demands on the spring's structural response. The scroll spring's minimum clearance is a key indicator of its quality.

[0075] The method for detecting the minimum gap of an object using a visual inspection system is to extract the edges on both sides of the gap and set discrete points on both edges. The minimum distance between the discrete points on both sides is calculated to obtain the minimum value to determine the minimum gap. The difficulty in detecting the gap of a spiral spring lies in the fact that the spiral spring has the characteristic of being continuously wound as a whole and radially superimposed as a whole. That is, the gap and the spring body are in a continuous winding and stacked form as a whole, with no boundary features between the layers. Therefore, there are at least the following problems: First, the discrete points on one side of the gap will be used to calculate the distance with the discrete points in other layers, wasting computing power; second, the thickness of the spring body is difficult to distinguish from the gap between the springs, that is, it is difficult to determine whether the calculated minimum distance is the thickness of the spring.

[0076] The detection method includes the following steps:

[0077] Step S1: collecting an image of the top surface of the scroll spring 8 and extracting the image edge; the extracted image edge corresponds to the edge of the scroll spring 8;

[0078] Step S2: As shown in FIG10 , the posture coordinate system of the scroll spring 8 is determined, and the image edge is parameterized in the posture coordinate system. Determining the posture coordinate system of the scroll spring 8 includes the following steps S2.1-S2.2:

[0079] Step S2.1: Identify and locate the image features corresponding to the first hook 81 and the second hook 82 from the image; since the shapes of the first hook 81 and the second hook 82 are stable and have great differences relative to the spiral spring 8 body, they are easy to identify and locate from the image.

[0080] Step S2.2: extracting a feature point A and a feature point B from the image feature area of ​​the first hook 81 and the second hook 82, and aligning the line segments where the two feature points are located with the posture coordinate axis and the posture coordinate origin;

[0081] Step S3: As shown in FIG11 , a dividing line is set in the attitude coordinate system. The dividing line divides the image edge into at least two regions. The dividing line radially passes through the scroll spring 8 . At this time, the image edge of each divided region is a group of arc segments arranged at intervals.

[0082] Step S4: As shown in FIG12 , calibrate each pair of adjacent arc segments corresponding to the gap of the scroll spring 8. Specifically, exclude the outermost and innermost arc segments, and then use the arc segments that are adjacent to each other in the radial direction as the arc segments corresponding to the gap of the scroll spring 8. Specifically, there is definitely no minimum gap between the hooked portions of the first hook 81 and the second hook 82. Therefore, the image edges corresponding to the first hook 81 and the second hook 82 can be removed first.

[0083] Step S5: As shown in FIG13 , a set of discrete points is taken on the calibrated arc segment, and the distance between each discrete point on the calibrated arc segment and each discrete point on the corresponding arc segment is calculated;

[0084] Step S6: If the calculated spacing between the discrete points is smaller than the preset value, the size is judged to be unqualified; otherwise, it is judged to be qualified.

[0085] It should be noted that extracting image edges and identifying and locating image features corresponding to the first hook 81 and the second hook 82 from the image are basic functions of existing visual inspection tools, and the specific methods are not described here.

[0086] The above method first determines the scroll spring's posture coordinate system. Based on this, it can achieve radial segmentation of the edge image using preset cutting lines. The edge image after radial segmentation is a set of arc segments set at intervals. By calibrating each pair of arc segments on both sides of the gap one by one, and then calculating the distance between the discrete points of each calibrated pair of arc segments, and comparing the distance value with the preset value, it can accurately determine whether the scroll spring gap is qualified.

[0087] In this embodiment, in step S2.2, the posture coordinate system is a rectangular coordinate system, the line connecting the feature points is the x-axis, and the direction from A to B is the positive direction. Specifically, the midpoint of line segment AB is taken as the origin of the posture coordinate system.

[0088] In this embodiment, in step S2.2, the characteristic points A and B are the centers of the inscribed fitting circles of the first hook portion 81 and the second hook portion 82 respectively.

[0089] Generally, using the endpoint positions of the first hook 81 and the second hook 82 as feature points will cause the deviation of the endpoint positions of each spiral spring to cause the posture coordinate system generated by each spiral spring to deviate greatly from the actual posture of the spiral spring. In the present application, since the overall position of the first hook 81 and the second hook 82 is relatively stable with the spiral spring 8 body, the center of the inscribed fitting circle of the first hook 81 and the second hook 82 is used as the feature point, which can ensure that the posture coordinate system generated by each spiral spring is relatively stable. It should be noted that according to actual experience, especially for the spiral spring used in the phase adjuster of the automobile engine as shown in Figure 9, the position of the minimum gap of the spiral spring can be roughly determined, thereby improving the stability of the posture coordinate system, helping to generate the corresponding cutting line to narrow the minimum gap positioning range, thereby saving computing power.

[0090] It should be noted that obtaining an inscribed fitting circle based on the first hook 81 and the second hook 82 is a basic function of existing visual inspection tools, and the specific method will not be repeated here.

[0091] In this embodiment, after determining the posture coordinate system of the spiral spring 8, the characteristic point C corresponding to the position of the inner hole of the spiral spring 8 is calibrated; in this embodiment, the characteristic point C corresponds to the center of the fitting circle of the inner hole of the spiral spring 8, and can also be directly preset from the posture coordinate system; the method of obtaining discrete points in step S5 is specifically as follows: the endpoints of each arc segment are connected to the characteristic point C to form an angle, and a group of rays passing through the characteristic point C are set at equal intervals between the angles, and the intersection of the ray and the arc is the discrete point of the arc segment.

[0092] Based on the above method, the uniformity of the discrete point extraction can be ensured. In this embodiment, the number of segmentation lines in step S3 is 2, which are rays passing through the feature point C.

[0093] In this embodiment, step S6 further includes the following steps:

[0094] Step S6.1: Compare the distances between discrete points to obtain the minimum distance value, and calibrate a pair of discrete points corresponding to the minimum distance value; specifically, if the distance between the pair of discrete points is less than a preset value, the size is judged to be unqualified; if the distance between the pair of discrete points is greater than the preset value, execute step S6.2;

[0095] Step S6.2: intercept the pair of arc segment areas where the pair of discrete points calibrated in step S6.1 are located, re-take a more dense set of discrete points for the intercepted pair of arc segments, calculate the distance between each discrete point on the intercepted arc segment and each discrete point on the corresponding arc segment; compare the obtained distance with the preset value again to determine whether the size is qualified.

[0096] Based on the above method, the detection accuracy can be improved. Specifically, the method of intercepting the arc segment is to intercept the preset width on both sides of the corresponding calibration discrete point.

[0097] The technical principles of the present invention have been described above in conjunction with specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will be able to conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. A method for detecting the minimum clearance of a scroll spring, characterized in that: Used to detect whether the minimum gap of a spiral spring (8) is qualified, the inner end and the outer end of the spiral spring (8) are respectively provided with a first hook (81) and a second hook (82), and the detection method comprises the following steps: Step S1: collecting the top surface image of the scroll spring (8) and extracting the image edge; Step S2: determining the posture coordinate system of the scroll spring (8) and parameterizing the image edge in the posture coordinate system; wherein determining the posture coordinate system of the scroll spring (8) comprises the following steps S2.1 and S2.2: Step S2.1: Identify and locate image features corresponding to the first hook (81) and the second hook (82) from the image; Step S2.2: extracting a feature point A and a feature point B from the image feature area of ​​the first hook (81) and the second hook (82), respectively, and making the line segments where the two feature points are located correspond to the posture coordinate axis and the posture coordinate origin; Step S3: setting a dividing line in the attitude coordinate system, wherein the dividing line divides the image edge into at least two areas, and the dividing line radially penetrates the scroll spring (8). At this time, the image edge of each divided area is a group of arc segments arranged at intervals; Step S4: calibrating each pair of adjacent arc segments corresponding to the gap of the scroll spring (8); Step S5: taking a set of discrete points on the calibrated arc segment, and calculating the distance between each discrete point on the calibrated arc segment and each discrete point on the corresponding arc segment; Step S6: If the calculated spacing between discrete points is smaller than a preset value, the size is judged to be unqualified; otherwise, it is judged to be qualified.

2. A method for detecting the minimum gap of a scroll spring according to claim 1, characterized in that: In step S2.2, the posture coordinate system is a rectangular coordinate system, the line connecting the feature points is the x-axis, and the direction from A to B is the positive direction.

3. The method for detecting the minimum clearance of a scroll spring according to claim 1, characterized in that: In step S2.2, the characteristic points A and B are respectively the centers of the inscribed fitting circles of the first hook portion (81) and the second hook portion (82).

4. The method for detecting the minimum clearance of a scroll spring according to claim 1, characterized in that: After determining the posture coordinate system of the scroll spring (8), calibrate the characteristic point C corresponding to the position of the inner hole of the scroll spring (8); the process of obtaining discrete points in step S5 is specifically as follows: the endpoints of each arc segment are connected to the characteristic point C to form an angle, and a group of rays passing through the characteristic point C are arranged at equal intervals between the angles, and the intersection of the ray and the arc is the discrete point of the arc segment.

5. The method for detecting the minimum clearance of a scroll spring according to claim 1, characterized in that: The step S6 also includes the following steps: Step S6.1: Compare the distances between discrete points to obtain a minimum distance value, and calibrate a pair of discrete points corresponding to the minimum distance value; Step S6.2: intercept the pair of arc segments where the pair of discrete points calibrated in step S6.1 are located, and A new set of denser discrete points is taken for the arc segment, and the distance between each discrete point on the intercepted arc segment and each discrete point on the corresponding arc segment is calculated; the obtained distance is compared with the preset value again to determine whether the size is qualified.

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