CN112969289B

CN112969289B - Feeding fool-proof method for PCB

Info

Publication number: CN112969289B
Application number: CN202110136200.XA
Authority: CN
Inventors: 黄博; 左鼎
Original assignee: Shenzhen Guanyun Intelligent Control Technology Co ltd
Current assignee: Shenzhen Guanyun Intelligent Control Technology Co ltd
Priority date: 2021-02-01
Filing date: 2021-02-01
Publication date: 2022-08-09
Anticipated expiration: 2041-02-01
Also published as: CN112969289A

Abstract

The invention discloses a PCB feeding fool-proofing method, which is used for judging the material taking effect of a gripping device for gripping a PCB from PCB stacking, and comprises the following steps: acquiring a first side image before each grabbing operation and a second side image after the grabbing operation of the PCB stacking material through a visual assembly; determining the grabbing state of the PCB stacked material after one grabbing operation according to the first side surface image and the second side surface image; and judging whether the grabbing operation is normal or not according to the grabbing state. The invention installs the visual component at the side of the PCB stack to obtain the side images before and after the grabbing operation, and judges whether the material taking is correct or not through the side images before and after the grabbing operation, thereby solving the problem of material taking errors such as excessive material taking, missing material taking, plate sticking, deviation and the like.

Description

Feeding fool-proof method for PCB

Technical Field

The invention belongs to the technical field of visual sensing, and particularly relates to a PCB feeding fool-proofing method.

Background

The front end of the PCB dividing and counting machine is a full-automatic feeding device, a material taking mechanical arm takes a PCB from orderly PCB stacking materials to a specified position every time, and after each PCB is taken, the PCB stacking materials integrally rise to form a grid.

After snatching the operation at every turn, because board size, thickness, shape, fretwork degree are different, the PCB board in the PCB board folded material can appear following several kinds of condition influences and snatch the judgement of effect:

1. deviation (including inward deviation and outward deviation), the side surface of the PCB on the surface of the PCB stacking material is not flat, and after some PCB stacking materials are grabbed, adjacent PCBs can deviate inwards or outwards to influence the next material taking;

2. missing fetching, namely, a manipulator does not effectively adsorb and grab a PCB in the fetching process, so that missing grabbing is caused;

3. grab more, it is too big to get the material in-process to have vacuum negative pressure, has certain probability can get two or three PCB boards.

Therefore, a fool-proof method is needed to detect the positions of the PCBs before and after material taking, and determine whether to take more, miss and shift.

The current laser thickness measuring sensor can only measure a single point or a single line generally, and when a board is provided with holes or is hollow, the thickness measuring sensor is ineffective; in addition, the thin plate (less than or equal to 1 mm) often warps and deforms, is not on a plane, and cannot be measured accurately.

Disclosure of Invention

The invention provides a PCB feeding fool-proofing method, which can effectively detect abnormal conditions such as excessive taking, missing taking, deviation and the like in the feeding process.

In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:

the utility model provides a PCB board material loading prevents slow-witted method for judge grabbing device and snatch the material effect of getting of PCB board once from PCB board is folded the material, include:

acquiring a first side image before each grabbing operation and a second side image after the grabbing operation of the PCB stacking material through a visual assembly;

determining the grabbing state of the PCB stacked material after one grabbing operation according to the first side surface image and the second side surface image;

and judging abnormal information according to the grabbing state.

Further defined, the vision assembly includes:

a high-pixel camera for capturing a first side image and a second side image;

an optical lens for focusing the first side image and the second side image;

a bar light source for emitting bar light matched to a side of the PCB stack, and,

and the corner prism can guide and project the strip light to the side face of the PCB stacking material.

Further, it is defined that the determining the grabbing state of the PCB plate stack after one grabbing operation according to the first side image and the second side image includes: the method comprises the following steps:

determining a first upper surface boundary position of the PCB stacking material according to the first side image;

searching the seam position between two adjacent PCBs from the boundary position of the upper surface;

calculating the thickness of the single PCB according to the seam position;

determining a second upper surface boundary position of the PCB stacking material after one grabbing operation is performed according to the second side surface image;

and determining the boundary change state of the PCB stacking material after one grabbing operation is performed according to the first upper surface boundary position and the second upper surface boundary position.

Further defined, determining a first upper surface boundary location of the PCB panel stack from the first side image includes:

converting the first side image into a grayscale image;

searching a boundary straight line which is greater than or equal to a set gray value for the first time from the upper part of the PCB stacking material to the direction vertical to the upper surface of the PCB stacking material;

and marking the position of the boundary straight line.

Further defined, the searching for the seam position between two adjacent PCBs from the upper surface boundary position includes:

searching a seam initial boundary straight line which is smaller than a set gray value for the first time from the position of the boundary straight line to the PCB stacking direction;

and continuously searching the seam tail end boundary straight line which is greater than or equal to the set gray value for the first time from the seam initial boundary straight line.

Further defined, the thickness of the single PCB board is calculated as follows:

the position of the boundary straight line is differed from the position of the boundary straight line at the tail end of the seam of the first seam to obtain the thickness of the first PCB;

the position of the straight line of the seam tail end boundary of the first seam is differed from the position of the straight line of the seam tail end boundary of the second seam to obtain the thickness of a second PCB;

by analogy, the thickness of the Nth PCB is obtained;

and carrying out arithmetic average on the thicknesses of the N PCB boards to obtain the thickness of a single PCB board.

Further, determining a boundary change state of the PCB panel stack after the one-time grabbing operation is performed according to the first upper surface boundary position and the second upper surface boundary position includes:

calculating the grabbing change distance of the boundary position of the first upper surface and the boundary position of the second upper surface;

and judging the error proportion of the grabbing variation distance compared with the thickness of the single PCB.

Further, the determining the abnormal information according to the capturing status includes:

comparing the error proportion with a set normal thickness floating proportion;

if the error ratio is smaller than or equal to the normal thickness floating ratio, the grabbing operation is normal;

if the error ratio is larger than the normal thickness floating ratio, the grabbing operation is abnormal, and abnormal reminding is carried out.

Further defined, a slide assembly capable of moving the vision assembly is also included, the slide assembly including:

a fixed base, and,

a sliding base capable of sliding the vision assembly relative to the stationary base.

Further inject, be equipped with the slide rail on the unable adjustment base, be equipped with the spout that matches with the slide rail on the sliding bottom, the method that vision subassembly passes through sliding bottom and slides for unable adjustment base includes:

determining the size and shape of the board body and the hollow degree in the board according to the PCB material to be grabbed;

the position of the sliding base is adjusted according to the size and the shape of the board body and the in-board hollow degree, so that the visual assembly can acquire a first side image and a second side image which are clear in the side face of the PCB stacking material.

According to the invention, the visual assembly is arranged on the side of the PCB stack to obtain the side images of the PCB before and after the grabbing operation, and whether the material is taken correctly is judged through the side images before and after the grabbing operation, so that the problems of material taking errors such as excessive material taking, missing material taking, plate sticking, deviation and the like are solved.

The method has high detection speed, works synchronously with the material taking of the manipulator, and does not occupy the operation time of the whole machine; the precision is high, and the thinnest PCB board of detectable 0.4 mm.

Drawings

Fig. 1 is a flowchart of a feeding fool-proofing method for a PCB board of the present application;

FIG. 2 is a flow chart of a grabbing state of the PCB stacking material after one grabbing operation according to the first side surface image and the second side surface image;

FIG. 3 is a flow chart of determining a first upper surface boundary position of a PCB stack from a first side image;

FIG. 4 is a flow chart of identifying the seam location between two adjacent PCBs;

FIG. 5 is a flow chart of calculating the thickness of a single PCB board;

FIG. 6 is a flowchart illustrating a boundary change state after a single grabbing operation is performed on a PCB stack according to a first top surface boundary position and a second top surface boundary position;

FIG. 7 is a schematic view of a first side image acquired;

FIG. 8 is a schematic diagram of a PCB warpage image;

FIG. 9 is a schematic view of a PCB with inwardly biased images;

FIG. 10 is a schematic view of an outward-biased image of a PCB

FIG. 11 is a schematic view of a feeding fool-proof structure of the PCB of the present application;

fig. 12 is a flow chart of the sliding of the vision assembly relative to the stationary base by the sliding base.

The notation in the figure is: 1-PCB stacking, 21-high pixel camera, 22-lens, 23-strip light source, 3-fixed base, 31-slide rail, 32-positioning hole and 4-sliding base.

Detailed Description

In order to facilitate understanding of those skilled in the art, the present invention will be further described with reference to the following examples and drawings, which are not intended to limit the present invention.

As shown in fig. 1, a feeding fool-proof method for PCB boards is used for judging the material taking effect of a gripping device for gripping the PCB boards from a PCB board stacking material, and comprises the following steps:

s10: acquiring a first side image before grabbing operation and a second side image after grabbing operation of the PCB stacked material each time through a visual component:

wherein, the vision subassembly includes high pixel camera, optical lens, bar light source and corner prism, and the theory of operation is: the strip light is emitted through the strip light source and irradiates the optical fiber to the side face of the PCB stacking material through the corner prism, so that the high-pixel camera and the optical lens can shoot clear first side face images and second side face images.

For the subsequent calculation of the first side image and the second side image, corresponding images can be obtained by shooting for multiple times, and the calculated values can be averaged, so that the stability and the precision of measurement can be improved.

In the specific implementation process, the high-pixel camera adopts an industrial camera with 130 ten thousand pixels, the optical lens selects a lens with 35mm focal length, the strip light source emits white light, and the strip light source is transmitted to the side face of the PCB stacking material through the 90-degree corner prism.

S20: determining the grabbing state of the PCB stacked material after one grabbing operation according to the first side surface image and the second side surface image

In this step, the change of the PCB stack after one grabbing operation is calculated according to the photographed first side image and second side image, so as to determine the grabbing state, as shown in fig. 2 specifically:

s21: determining a first upper surface boundary position of a PCB stack according to the first side image

The step is mainly to determine the position of the upper surface of the PCB stack before the grabbing operation, wherein the determination method of the boundary position of the first upper surface is shown in FIG. 3:

s211: and converting the first side image into a gray image, wherein the gray value range is 0-255, so that the PCB irradiated by the light in the converted first side image is obviously bright, and other parts (including seams between adjacent PCBs) are dark.

S212: and searching a boundary straight line which is greater than or equal to the set gray value for the first time from the upper part of the PCB stacking material to the direction vertical to the upper surface of the PCB stacking material, wherein the position where the gray value is changed from dark to light is the boundary position of the first upper surface of the PCB stacking material.

S213: the position of the boundary straight line is marked, and the boundary straight line is the reference datum position for later-stage calculation distance change, so that the boundary straight line is marked in advance to facilitate later calculation.

S22: searching the seam position between two adjacent PCBs from the boundary position of the upper surface

Since the adjacent two PCBs are not completely attached to each other, a seam with a certain width exists, which results in that only the width of the light-color part in the grayscale image cannot be considered for calculating the thickness of the single PCB, but the error caused by the width of the dark-color seam should be also considered, and the position of the seam can be confirmed according to the flow shown in fig. 4.

S221: firstly, a seam initial boundary straight line which is smaller than a set gray value for the first time is searched from the position of the boundary straight line to the PCB stacking direction, namely, the position of the bright PCB is ended, and the position of the seam is started.

S222: and continuously searching the straight line of the seam end boundary which is greater than or equal to the set gray value for the first time from the straight line of the seam initial boundary, namely the position where the seam position is ended.

The distance between the straight line of the seam initial boundary and the straight line of the seam tail end boundary is the error caused by the width of the seam.

S23: calculating the thickness of the single PCB according to the seam position

Correcting the thickness of the single PCB according to the error caused by the width of the gap, as shown in FIG. 5:

s231: firstly, the position of the boundary straight line is differed from the position of the seam tail end boundary straight line of the first seam to obtain the thickness of the first PCB, namely, the thickness of the first PCB of the PCB stacking material is calculated.

S232: and (4) making a difference between the position of the straight line at the seam tail end of the first seam and the position of the straight line at the seam tail end of the second seam to obtain the thickness of the second PCB.

S233: by analogy, the thickness of the Nth PCB can be calculated, and then the average value of the thicknesses of the N PCBs on the surface of the PCB stacking material is used as the thickness of a single PCB, so that the error influence caused by the width of the gap is reduced.

In the above steps, the average value of the thicknesses of 2-3 PCB boards on the surface of the PCB board stacking material can be selected as the thickness of a single PCB board according to the actual situation.

S24: determining the boundary position of the second upper surface of the PCB stack after one grabbing operation is performed according to the second side surface image

The boundary position of the second upper surface of the PCB stacked material after the primary grabbing operation is performed may be calculated according to the steps S211 to S212, which is not described herein again.

S25: determining the boundary change state of the PCB stack after one grabbing operation is performed according to the first upper surface boundary position and the second upper surface boundary position

This step is mainly according to the PCB board stack and is executed the position change of PCB board stack upper surface after once snatching the operation to judge and snatch the effect, as shown in fig. 6 specifically:

s251: firstly, calculating the grabbing change distance of the boundary position of the first upper surface and the boundary position of the second upper surface, wherein the grabbing change distance is the position change of the upper surface of the PCB stacking material after one grabbing operation is performed.

S252: and judging the error proportion of the grabbing variation distance compared with the thickness of the single PCB.

S30: judging abnormal information according to the grabbing state

In the step, the error proportion is compared with the set normal thickness floating proportion, so that the grabbing operation effect is judged. If the error ratio is smaller than or equal to the normal thickness floating ratio, the grabbing operation is normal; if the error ratio is larger than the normal thickness floating ratio, the grabbing operation is abnormal, and abnormal reminding is carried out.

In the present example, the normal thickness fluctuation ratio was set to 40%.

The following explains the execution flow of the present application in conjunction with the actual operation process.

As shown in fig. 7, first, a first side image is obtained to determine a position of a first upper surface boundary, that is, a position of a straight line a is taken as a reference line, the position of the first upper surface boundary is measured to be 819, a straight line b is a first seam initial boundary straight line, a position of a first seam end boundary straight line (that is, a straight line c) is obtained, the position of the first seam end boundary straight line is measured to be 738, and similarly, a position of a second seam end boundary straight line (that is, a straight line e) is measured to be 653, so that a thickness D1 of the first PCB board can be 819-738=81, a thickness D2-D1= 819-81 =85, and thus a thickness of the single PCB board can be estimated to be (81 + 85)/2 = 83.

And then, carrying out one-time grabbing operation on the PCB stacked material, shooting a second side image after the grabbing operation, acquiring a second upper surface boundary position of the PCB stacked material after the one-time grabbing operation is carried out, and judging the effect of the grabbing operation through actually measuring the second upper surface boundary position data.

Generally, after a grabbing operation is performed, there are the following situations:

firstly, the normal thickness floating proportion is set to be 40%, namely, the change of the boundary position of the second upper surface to the boundary position of the first upper surface after the PCB is grabbed once is within the range of 83 +/-33.2 (namely 50-116), which belongs to normal grabbing.

1. In the grabbing, the boundary position of the second upper surface is 740 after the PCB is grabbed, that is, the boundary before and after grabbing is reduced 819-.

And the state change of the second upper surface boundary of the second side surface image is within the normal thickness floating proportion, which indicates that the PCB grabbing operation is normal.

2. As shown in fig. 8, in the current grabbing, the second upper surface boundary position a1 measured after the PCB is grabbed is 800, that is, the front and rear grabbing boundaries are only reduced by 19, and the error ratio = (83-19)/83 = 77.1%.

And the state change of the second upper surface boundary position a1 of the second side surface image exceeds the normal thickness floating proportion, which indicates that the PCB grabbing operation is abnormal, and an abnormal alarm is given, and after the inspection, the reason is that the first PCB on the surface of the PCB stacked material after the grabbing operation has a warping phenomenon, and the straight line a1 to the straight line a2 form the thickness of the first PCB after the grabbing operation, so that the second upper surface boundary position is higher than the expected position.

3. As shown in fig. 9, in the grabbing, the position b2 of the second upper surface boundary measured after the PCB is grabbed is 663, that is, the boundary before and after grabbing is reduced by 819 + 663=156, which is far beyond the normal thickness floating ratio, and therefore it is determined that the grabbing operation is abnormal. After inspection, the reason is that the actual second upper surface boundary position a2 in the second side image is not clear due to inward bias pulling of the first PCB on the surface of the PCB laminate after the grabbing operation, but the surface of the second PCB in the PCB laminate after the grabbing operation is mistakenly identified, so that the boundary distance obtained before and after grabbing is obviously increased.

4. As shown in fig. 10, in the current grabbing, the second upper surface boundary position a3 measured after the PCB is grabbed is 733, that is, the boundary before and after grabbing is reduced 819 + 733=86, and falls within the range of the normal thickness floating proportion, but the detection result (the distance between the straight line a3 and the straight line b 3) of the thickness of the first PCB on the stacked surface of the PCB after grabbing operation is 733 + 584=149, which is higher than the normal thickness floating proportion, and thus it is determined that the grabbing operation is abnormal. Through the inspection, the reason lies in snatching the outside inclined to draw of the first PCB board on operation back PCB board folded material surface, and the light source shines back PCB board folded material side like this and makes the PCB board luminance that is close to the camera lens high, leads to not having obvious gap position between two adjacent PCB boards in PCB board folded material surface in the second side image and can supply discernment, will regard two adjacent PCB board thickness misidentification as a PCB board thickness like this.

Of course, in addition to the above four common grasping operation cases, there are also multiple grasping cases, i.e., two PCB boards are grasped at the same time, which is not allowed by the grasping operation.

Consider that the PCB board has different because of its size of material number, thickness, shape and fretwork each degree, consequently for the clear first side image and the second side image of better acquireing PCB board stack side, can set up a sliding assembly and adjust the position of vision subassembly, if for example there is the fretwork condition towards the PCB board of camera lens one side, the light source shines this fretwork side like this, the luminance of PCB self reflection can be unobvious for the gap position between PCB board and the adjacent PCB board is difficult for distinguishing, or the PCB board is too thin, need be closer to PCB board stack side with the camera lens.

Referring to fig. 11, in the present application, the sliding assembly at least includes a fixed base 3 and a sliding base 4 capable of sliding the visual assembly relative to the fixed base 3, so that when the position of the visual assembly needs to be adjusted, the position of the visual assembly can be changed by the position of the sliding base 4 on the fixed base 3, thereby obtaining the position of the new visual assembly.

Specifically, the fixed base 3 is provided with a slide rail 31, the sliding base 4 is provided with a slide groove (not shown in the figure) matched with the slide rail 31, and the flow of the visual component sliding relative to the fixed base 3 through the sliding base 4 is as shown in fig. 12, specifically:

p10: determining the size and shape of the board body and the hollow degree in the board according to the PCB material to be grabbed

The lens 22 can be adjusted to be far and near according to the size and the thickness of the PCB, and the position of the high-pixel camera 21 relative to the PCB stacking material 1 is adjusted according to the in-board hollow degree of the PCB.

P20: the position of the sliding base 4 is adjusted according to the size, the shape and the in-board hollow degree of the board body, so that the visual component can acquire a first side image and a second side image which are clear on the side of the PCB stacking material 1, after the position of the sliding base 4 is determined, the high-pixel camera 21, the lens 22 and the like of the visual component can be fixed through the positioning hole 32 on the sliding rail 31, and the position of the strip-shaped light source 23 can change the transmission direction through the corner prism.

The feeding fool-proofing method for the PCB provided by the application is described in detail above. The description of the specific embodiments is only intended to facilitate an understanding of the methods of the present application and their core concepts. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of the claims of the present application.

Claims

1. The utility model provides a PCB board material loading prevents slow-witted method for judge grabbing device and snatch the material effect of getting of PCB board once from PCB board is folded the material, a serial communication port, include:

according to the first side surface image and the second side surface image, the grabbing state of the PCB stacking material after one grabbing operation is determined, and the method specifically comprises the following steps:

calculating the thickness of the single PCB according to the seam position;

determining a boundary change state of the PCB stacking material after one-time grabbing operation is performed according to the first upper surface boundary position and the second upper surface boundary position;

and judging abnormal information according to the grabbing state.

2. The PCB feeding fool-proofing method of claim 1, wherein the vision assembly comprises:

a high-pixel camera for capturing a first side image and a second side image;

an optical lens for focusing the first side image and the second side image;

3. The PCB feeding fool-proofing method of claim 1, wherein the determining the boundary position of the first upper surface of the PCB stack according to the first side image comprises:

converting the first side image into a grayscale image;

and marking the position of the boundary straight line.

4. The PCB feeding fool-proofing method of claim 3, wherein the searching for the seam position between two adjacent PCBs from the boundary position of the upper surface comprises:

5. The PCB feeding fool-proofing method of claim 4, wherein the thickness of the single PCB is calculated as follows:

by parity of reasoning, obtaining the thickness of the Nth PCB;

6. The PCB feeding fool-proofing method of claim 5, wherein the determining of the boundary change state of the PCB stack after the one-time grabbing operation is performed according to the first upper surface boundary position and the second upper surface boundary position comprises:

7. The PCB feeding fool-proofing method of claim 6, wherein the step of judging the abnormal information according to the grabbing state comprises the steps of:

comparing the error proportion with a set normal thickness floating proportion;

8. A PCB feeding fool-proofing method according to any one of claims 1-7, further comprising a sliding assembly capable of moving a vision assembly, wherein the sliding assembly comprises:

a fixed base, and,

9. The PCB feeding foolproof method of claim 8, wherein a slide rail is arranged on the fixed base, a slide groove matched with the slide rail is arranged on the slide base, and the method for the visual component to slide relative to the fixed base through the slide base comprises the following steps: