CN114952068A

CN114952068A - Welding quality detection method and detection device, welding device and control method thereof

Info

Publication number: CN114952068A
Application number: CN202210920176.3A
Authority: CN
Inventors: 成朋; 李晋升; 周毓坤; 谢媛媛; 冯保铭; 汤云潞; 张琦; 万柯; 耿杰
Original assignee: Jiangsu Contemporary Amperex Technology Ltd
Current assignee: Jiangsu Contemporary Amperex Technology Ltd
Priority date: 2022-08-02
Filing date: 2022-08-02
Publication date: 2022-08-30

Abstract

The application relates to the technical field of welding, in particular to a welding quality detection method and device, a welding device and a control method thereof. The welding quality detection method comprises the following steps: acquiring an ultrasonic chromaticity image of a part to be detected including a welding part, wherein different chromaticities correspond to different interface bonding degrees respectively in the ultrasonic chromaticity image; selecting a welding area in the ultrasonic chromaticity image; obtaining the chromaticity amplitude of each point in the welding area; and if the number of points of which the chromaticity amplitude is smaller than the first chromaticity threshold value in the points included in the welding area is larger than a first preset number, judging that the welding quality of the welding part is qualified. In the application, through acquiring the ultrasonic chromaticity image of the part to be detected, in the ultrasonic chromaticity image, different chromaticities respectively correspond to different interface combination degrees, so that the interface combination degree of the welding part can be reflected through the difference of the chromaticities in the image, namely, the welding quality is reflected, and therefore, the detection of the welding quality is accurate.

Description

Welding quality detection method and detection device, welding device and control method thereof

Technical Field

The present disclosure relates to the field of welding technologies, and in particular, to a welding quality detection method and device, a welding device, and a control method thereof.

Background

With the continuous development of battery technology, people have higher and higher requirements on the quality of batteries, so that an effective quality control means is of great importance. Welding is an important part in the production process of the battery, and due to the complexity of the welding process, defects such as welding holes, insufficient welding, incomplete welding and the like can be generated inevitably, and the defects seriously affect the cycle life and the safety performance of the battery. Therefore, it is particularly important to detect the welding quality of the battery.

The existing welding quality detection mode mainly judges the welding effect through metallographic phase detection penetration, or judges the welding effect through testing the direct current internal resistance value of a battery monomer, however, the existing detection method has the problems of low efficiency and low detection accuracy.

Disclosure of Invention

In view of the above, it is necessary to provide a welding quality detection method and detection apparatus, a welding apparatus, and a control method thereof, which are directed to the problems of low detection rate and low detection accuracy in the welding quality detection method of the related art.

In a first aspect, the present application provides a welding quality detection method for detecting welding quality of a welding site, the welding quality detection method including:

acquiring an ultrasonic chromaticity image of a part to be detected including a welding part, wherein different chromaticities correspond to different interface bonding degrees respectively in the ultrasonic chromaticity image;

selecting a welding area in the ultrasonic chromaticity image;

obtaining the chromaticity amplitude of each point in the welding area;

and if the number of points of which the chromaticity amplitude is smaller than the first chromaticity threshold value in the points included in the welding area is larger than a first preset number, judging that the welding quality of the welding part is qualified.

In the scheme, the ultrasonic chromaticity image of the part to be detected is obtained, and the welding quality of the welding part is judged by utilizing the ultrasonic chromaticity image, so that the welding part is not required to be damaged in the whole process, and the welding part is subjected to nondestructive testing, and 100% of total testing on the welding quality can be realized. In addition, only the ultrasonic image of the part to be detected is required to be acquired, the part to be detected does not need to be cut or connected to a circuit for detection like the prior art, and therefore the detection efficiency is high. On the other hand, in the ultrasonic chromaticity image, different chromaticities correspond to different interface combination degrees respectively, so that the interface combination degree of a welding part can be reflected through the difference of the chromaticities in the image, namely, the welding quality is reflected, and the detection of the welding quality is accurate.

In addition, the welding quality can be more accurately reflected by selecting the welding area and obtaining the chromaticity amplitude of each point in the welding area, wherein the chromaticity amplitude of each point in the welding area is used for representing the welding quality, and the size of the welding area and the penetration of the welding area are considered.

In addition, the first chromaticity threshold and the first preset number are ranges obtained in advance through experiments and research of the inventor of the application, the smaller the chromaticity amplitude is, the smaller the penetration data of the point is, the better the welding quality is, therefore, if the number of the points of which the chromaticity amplitude is smaller than the first chromaticity threshold is larger than the first preset number, that is, the number of the points of which the penetration reaches the standard in the welding area reaches a certain degree, the welding quality of the welding area can be judged to be qualified, and the judgment mode is accurate and simple.

In the welding region, the penetration can be characterized by the interface bonding state of two materials welded to each other, and can be reflected by the chromaticity amplitude in the ultrasonic chromaticity image, specifically, the difference in the bonding degree of each point on the interface is reflected in the ultrasonic chromaticity image, each corresponding to a different chromaticity amplitude. Therefore, the welding quality can be reflected according to the chromaticity amplitude of each point in the ultrasonic chromaticity image. In addition, since the welding portion usually covers a certain range, in order to reflect the welding quality of the welding portion as a whole, the chromaticity amplitude of each point in the welding region may be combined to comprehensively reflect the welding condition of the entire welding region. In other words, the quality of the welding quality is judged from two dimensions of the size of the welding area and the penetration depth, and the judgment is more accurate.

In some embodiments, the selecting the welding region in the ultrasonic colorimetric image specifically includes:

obtaining the chromaticity amplitude of each point in the ultrasonic chromaticity image;

selecting a first area in the ultrasonic chromaticity image, wherein the first area is an area distributed by each point with chromaticity amplitude within a first chromaticity amplitude range;

and taking a first area surrounded by a second area as a welding area, wherein the second area is an area distributed by points with chromaticity amplitude values within a second chromaticity amplitude range, and the first chromaticity amplitude range is smaller than the second chromaticity amplitude range.

Since the bonding degree between two different interfaces in the region around the welding region is significantly different compared to the welding region, the difference is reflected in the ultrasonic chromaticity image, and a significant boundary is displayed in the image due to the significant size difference of the chromaticity amplitude. The first region can thus be used as a welding region by finding such a first region which is distinguished from the chrominance amplitudes of the surrounding second region.

In some embodiments, if the number of points, of the points included in the welding area, whose chromaticity amplitude is smaller than the first chromaticity threshold value is greater than a first preset number, the welding quality of the welding portion is determined to be qualified, the method further includes:

calculating the area value of the welding area and obtaining the average value of the chromaticity amplitude of each point in the welding area;

and if at least one of the following conditions is met, determining that the welding quality of the welding part is unqualified:

the area value of the welding area is outside a first preset range;

the average value of the chromaticity amplitude of the welding area is outside a second preset range.

Like this, judge welding quality through two parameters of welding region or the chroma amplitude average value in welding region, as long as one of them parameter does not satisfy the requirement then can judge that welding quality is unqualified, judge comparatively accurately, avoided the probably condition of missing examining.

In some embodiments, acquiring an ultrasonic colorimetric image of a to-be-detected portion including a weld portion specifically includes:

acquiring an ultrasonic signal reflected by a part to be detected;

and generating an ultrasonic chrominance image of the part to be detected according to the ultrasonic signal.

In some embodiments, before acquiring the ultrasonic signal reflected by the site to be detected, the method further includes:

coating a coupling agent on a part to be detected;

and attaching the ultrasonic probe to the part to be detected coated with the coupling agent, and controlling the ultrasonic probe to send ultrasonic waves to the welding part.

The couplant is coated on the part to be detected, so that the acoustic resistance difference between a probe for emitting ultrasonic waves and the part to be detected can be reduced, the ultrasonic waves can penetrate into the part to be detected without damage, and images with higher quality can be obtained.

In a second aspect, the present application provides a control method of a welding apparatus, including:

judging the welding quality of the welding part by using the welding quality detection method;

and if the welding quality of the welding part is judged to be unqualified, stopping the welding operation of a welding mechanism in the welding device.

By using the welding quality detection method, the quality of the welding quality can be accurately and quickly detected, if the welding quality of the welding part is unqualified, the welding mechanism possibly fails, and at the moment, if the welding operation of the welding mechanism is stopped, the condition that a large quantity of unqualified battery cores are produced can be avoided.

In some embodiments, in the welding quality detection method, if an absolute value of a difference between the number of points, of which the chromaticity amplitude is smaller than the first chromaticity threshold value, and the first preset number is smaller than a second preset number, of the points included in the welding region, the welding by the welding mechanism is stopped, and the welding quality of the welding portion is detected by using a metallographic cutting method.

In the method, if the absolute value of the difference between the number of the points with the chromaticity amplitude smaller than the first chromaticity threshold and the first preset number is smaller than the second preset number, in other words, the number of the points with the chromaticity amplitude smaller than the first chromaticity threshold is located near the first preset number, it is proved that the welding quality is not qualified, and at this time, the operation of the welding machine of the welding mechanism can be stopped, and the welding quality of the welding part can be detected by other methods, such as a metallographic cutting method, so as to eliminate the possible welding quality problem, and make the detection of the welding quality more reliable.

In a third aspect, the present application provides a weld quality detection apparatus, in some embodiments, comprising:

the ultrasonic chromaticity acquisition device comprises a first acquisition module, a second acquisition module and a control module, wherein the first acquisition module is used for acquiring an ultrasonic chromaticity image of a part to be detected containing a welding part, and different chromaticities in the ultrasonic chromaticity image correspond to different interface bonding degrees respectively, and the part to be detected at least comprises the welding part; and

the selection module is used for selecting a welding area from the ultrasonic chromaticity image;

the second acquisition module is used for acquiring the chromaticity amplitude of each point in the welding area; and

and the judging module is used for judging that the welding quality of the welding part is qualified if the number of points of which the chromaticity amplitude is smaller than the first chromaticity threshold value in all the points in the welding area is larger than a first preset number.

Therefore, the quality of the welding quality is judged from the dimensions of the welding area and the depth of fusion, and the judgment is more accurate. Moreover, the first chromaticity threshold and the first preset number are ranges obtained in advance through experiments and research of the inventor of the application, the smaller the chromaticity amplitude is, the smaller the penetration data of the point is, the better the welding quality is, therefore, if the number of the points of which the chromaticity amplitude is smaller than the first chromaticity threshold is larger than the first preset number, that is, the number of the points of which the penetration reaches the standard in the welding area reaches a certain degree, the welding quality of the welding area can be judged to be qualified, and the judgment mode is accurate and simple.

In some embodiments, the selection module is specifically configured to:

In some embodiments, the determining module is specifically configured to: calculating the area value of the welding area and obtaining the average value of the chromaticity amplitude of each point in the welding area; and if at least one of the following conditions is met, determining that the welding quality of the welding part is unqualified:

the area value of the welding area is outside a first preset range;

In some embodiments, the first obtaining module is specifically configured to:

acquiring an ultrasonic signal reflected by a part to be detected;

In a fourth aspect, the present application provides a welding quality detecting apparatus, including:

an ultrasonic probe for emitting ultrasonic waves to a part to be detected including a welding part;

the ultrasonic receiver is used for receiving the ultrasonic signal reflected by the part to be detected and generating an ultrasonic chromaticity image of the part to be detected from the ultrasonic signal; and

a processor electrically connected to the ultrasonic receiver, the processor configured to:

selecting a welding area in the ultrasonic chromaticity image;

obtaining the chromaticity amplitude of each point in the welding area;

In some embodiments, the processor is further specifically configured to:

calculating the area value of the welding area and obtaining the average value of the chromaticity amplitude of each point in the welding area; and if at least one of the following conditions is met, determining that the welding quality of the welding part is unqualified:

the area value of the welding area is outside a first preset range;

In some embodiments, the detection device further comprises a display electrically connected to the ultrasonic receiver, and the display is for displaying the ultrasonic colorimetric image. Therefore, the interface bonding condition of the welding part can be conveniently and visually observed by an operator.

In a fifth aspect, the present application provides a welding device comprising: a welding mechanism; and a welding quality detection device, wherein the welding quality detection device is the welding quality detection device.

In some embodiments, the welding device further comprises a controller electrically connected to the processor; the controller is used for controlling the welding mechanism to stop welding operation when the processor judges that the welding quality of the welding part is unqualified.

If the processor judges that the welding quality of the welding part is unqualified, the welding mechanism possibly fails, and at the moment, if the controller controls the welding operation of the welding mechanism to stop, the situation that a large quantity of unqualified battery cores are produced can be avoided.

In a sixth aspect, the present application provides a welding quality detection apparatus, including a memory and a processor, where the memory stores a computer program, and the processor implements the welding quality detection method and the control method of the welding apparatus when executing the computer program.

In a seventh aspect, the present application provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the aforementioned welding quality detection method, and the aforementioned steps of the control method of the welding apparatus.

In an eighth aspect, the present application provides a computer program product comprising a computer program which, when executed by a processor, implements the aforementioned weld quality detection method, and the aforementioned steps of the control method of the welding apparatus.

Drawings

FIG. 1 is a schematic flow chart of a weld quality detection method provided by some embodiments of the present application;

FIG. 2 is a schematic illustration of an ultrasonic colorimetric image obtained in a weld quality inspection method provided by some embodiments of the present application;

FIG. 3 is a flowchart illustrating specific steps for selecting a welding area in an ultrasonic chromaticity image in a welding quality detection method according to some embodiments of the present application;

FIG. 4 is a schematic structural diagram of a portion to be detected in a welding quality detection method according to some embodiments of the present disclosure;

fig. 5 is a schematic structural diagram of an interposer to be tested in a method for testing solder quality according to some embodiments of the present disclosure;

FIG. 6 is a schematic view of an ultrasonic colorimetric image acquired for the interposer of FIG. 5;

fig. 7 is a schematic structural diagram of another interposer to be tested in the method for testing solder quality according to some embodiments of the present application;

FIG. 8 is a schematic view of an ultrasonic colorimetric image acquired for the interposer of FIG. 7;

FIG. 9 is a schematic diagram of a weld quality detection apparatus according to some embodiments of the present disclosure;

FIG. 10 is a schematic diagram of another configuration of a weld quality detection apparatus according to some embodiments of the present disclosure;

fig. 11 is a schematic structural diagram of a welding device according to some embodiments of the present application.

The reference numbers illustrate:

110. an ultrasonic probe; 120. an ultrasonic receiver; 140. a wire;

200. a battery cell; 210. a pole column; 220. a patch; 221. a first transfer tab; 222. a second patch; 230. a top cover; 240. a housing; 250. welding parts;

300. 400, a welding quality detection device; 310. a first acquisition module; 321. selecting a module; 322. a second acquisition module; 323. a decision module;

410. a processor; 420. a display;

500. a welding device; 510. a welding mechanism; 520. and a controller.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiment in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and therefore the application is not limited to the specific embodiments disclosed below.

In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "above," and "over" a second feature may be directly on or obliquely above the second feature, or simply mean that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Welding is an important part in the production process of the battery, and due to the complexity of the welding process, defects such as welding holes, insufficient welding, incomplete welding and the like are inevitably generated, and the defects seriously affect the cycle life and the safety performance of the battery. Therefore, it is particularly important to detect the welding quality of the battery. However, the complex background around the weld and the interference of the texture of the weld itself can cause great difficulties in weld quality detection. Because the welding quality of a welding part cannot be directly judged by naked eyes, the conventional welding detection method comprises mechanical force detection, resistance measurement detection, large-current voltage drop or temperature rise detection, wherein the mechanical force detection mainly detects the welding quality by pulling, prying and other modes, is generally only suitable for spot inspection and has certain destructiveness; the detection accuracy of resistance detection, large-current voltage drop or temperature rise detection is poor, and meanwhile, certain damage to the battery can be caused, so that the method is not suitable for full detection. Therefore, the existing detection method has the problems of low efficiency and low detection accuracy.

In order to solve the problems of low detection efficiency and low detection accuracy in the welding quality detection process in the related technology, the inventor of the application determines the technical scheme of obtaining the ultrasonic chromaticity image of the part to be detected and judging the welding quality by using the ultrasonic chromaticity image through deep research, and in the ultrasonic chromaticity image, different chromaticities respectively correspond to different interface combination degrees, so that the interface combination degree of the welding part can be reflected through the difference of the chromaticities in the image, namely, the welding quality is reflected, and the detection of the welding quality is more accurate.

The welding quality detection method disclosed by the embodiment of the application is used for detecting the welding quality of the welding part, wherein the welding method for forming the welding part comprises but is not limited to laser welding, ultrasonic welding, resistance welding, high-frequency induction welding and other modes. The welding site to be detected may also be various.

Fig. 1 is a schematic flow chart of a welding quality detection method according to some embodiments of the present disclosure.

Referring to fig. 1, in a first aspect, some embodiments of the present application provide a welding quality detection method for detecting welding quality of a welding site, the welding quality detection method including:

s10, obtaining an ultrasonic chromaticity image of a part to be detected including a welding part, wherein in the ultrasonic chromaticity image, different chromaticities respectively correspond to different interface bonding degrees;

s20, selecting a welding area in the ultrasonic chromaticity image;

s30, obtaining the chromaticity amplitude of each point in the welding area;

and S40, if the number of the points with the chromaticity amplitude smaller than the first chromaticity threshold value in the points included in the welding area is larger than a first preset number, judging that the welding quality of the welding part is qualified.

The welding part is required to be included in the range of the part to be detected, so that the obtained ultrasonic chromaticity image of the part to be detected can include an area corresponding to the welding part, and an unwelded area is arranged outside the welding area corresponding to the welding part, so that the welding part can be accurately distinguished from the ultrasonic chromaticity image.

The ultrasonic chromaticity image is an imaging image of different chromaticities converted by sending ultrasonic waves to a part to be detected and utilizing the ultrasonic waves reflected by the part to be detected.

In the ultrasonic chromaticity image, different chromaticities correspond to different interface bonding degrees respectively, which means that the bonding degrees between two interfaces are different in a welded part and an unwelded part in a part to be detected. Specifically, in the ultrasonic image, darker color (larger chromaticity amplitude) indicates that the energy transmittance is poor at the position, and the reflected signal is strong, which indicates that the welding effect is poor at the position, and the interface bonding is defective or even non-bonded. Conversely, the lighter the color (the smaller the chromaticity amplitude), the better the energy permeability at that location, and the weaker the signal reflected back, indicating that the welding effect at that location is good, and the interface bonding is firm and flawless.

In addition, the first chroma threshold and the first preset number are ranges obtained in advance through experiments and researches of the inventor of the application, the smaller the chroma amplitude is, the smaller the penetration data of the point is, the better the welding quality is, therefore, if the number of the points of which the chroma amplitudes are smaller than the first chroma threshold is larger than the first preset number, namely the number of the points of which the penetration reaches the standard in the welding area reaches a certain degree, the welding quality of the welding area can be judged to be qualified, and the judgment mode is accurate and simple.

It is understood that if the number of points, of the points included in the welding region, whose chromaticity amplitude is smaller than the first chromaticity threshold value is smaller than or equal to the first preset number, it is determined that the welding quality of the welding portion is not good. In the embodiment of the application, in the ultrasonic colorimetric image, a welding area is selected to represent an actual area where welding occurs. In the whole range of the welding area, partial points may not be welded completely, the partial points are welded completely, at this time, the number of the points of which the chromaticity amplitude is smaller than the first chromaticity threshold value is larger than a first preset number, on one hand, the number of the points representing that the welding is completed reaches the first preset number, namely the number of the points completing the welding reaches the standard, and the dimension of the percentage of the points completing the welding in the total welding area is judged; on the other hand, in the points where welding is completed, the chroma amplitude reflects the depth of penetration at the point, that is, not only the number of the points where welding is completed is considered, but also the points where the penetration reaches the standard (the chroma amplitude is smaller than the first chroma threshold value) are selected from the points where welding is completed.

In addition, as described above, the chromaticity amplitude of each point included in the welding region is acquired, where each point in the ultrasonic chromaticity image is determined according to the scanning accuracy of the ultrasonic emitting device, for example, the ultrasonic probe, and for example, it is possible to set the scanning accuracy of the scanning of the ultrasonic probe to 2mmX2mm by setting, even if a range having a size of 2mmX2mm in the actual welding region corresponds to one point in the ultrasonic chromaticity image. It is understood that the scanning accuracy including but not limited to 2mmX2mm can be determined according to actual needs.

In the embodiment of the application, the welding quality can be more accurately reflected by selecting the welding area and obtaining the chromaticity amplitude of each point in the welding area, wherein the chromaticity amplitude of each point in the welding area is used for representing the welding quality, and meanwhile, the size of the welding area and the penetration of the welding area are considered.

As described above, the ultrasonic colorimetric image reflects the interface bonding condition of the entire part to be detected, and here, the welding area corresponding to the welding part can be selected from the ultrasonic colorimetric image, and the welding quality of the welding part can be judged by using the image of the welding area.

Fig. 2 is a schematic diagram of an ultrasonic colorimetric image obtained in a welding quality inspection method according to some embodiments of the present application.

Referring to fig. 2, the region indicated by reference numeral H is a welding region H selected in the ultrasonic chromaticity image.

It should be noted that the actually obtained ultrasonic chromaticity image is a color map, and the color map is represented by graying out the color map according to the requirements of the patent application document for the drawings, and the

chromaticity amplitudes

0, 125, 250, 375, 500 shown in fig. 2 actually represent different chromaticities although the grays shown in the grayscale map are similar or similar. In fig. 2, the substantially circular region located at the center is a welding region H. In fig. 2, the horizontal axis and the vertical axis are distances, and the actual size of the area of the welding portion can be indirectly reflected by calculating the area value of the welding region H.

In the specific implementation, the corresponding relationship between the area value of the welding area and the actual welding area of the welding part can be obtained through a previous experiment or simulation.

Fig. 3 is a flowchart illustrating specific steps of selecting a welding area in an ultrasonic chromaticity image in a welding quality detection method according to some embodiments of the present application.

In some embodiments of the present application, referring to fig. 3, step S20 is to select a welding region in the ultrasonic chromaticity image, which specifically includes:

s2110, obtaining the chromaticity amplitude of each point in the ultrasonic chromaticity image;

s2120, selecting a first area in the ultrasonic chromaticity image, wherein the first area is an area distributed by each point with chromaticity amplitude within a first chromaticity amplitude range;

s2130, a first area surrounded by a second area is used as a welding area, where the second area is an area where chromaticity amplitude values are distributed at points within a second chromaticity amplitude range, and the first chromaticity amplitude range is smaller than the second chromaticity amplitude range.

Since the bonding degree between two different interfaces in the region around the welding region H is significantly different from that in the welding region H, the boundary is reflected in the ultrasonic chromaticity image because the chromaticity amplitude is significantly differentiated, and the boundary is significantly displayed in the image. The first region can thus be used as a welding region by finding such a first region which is distinguished from the chrominance amplitudes of the surrounding second region.

The first chroma amplitude range and the second chroma amplitude range may be obtained through a previous experiment or simulation. The first chromaticity amplitude range is the range of corresponding chromaticity amplitude when the welding quality of the welding part is qualified, and the second chromaticity amplitude range is the range of corresponding chromaticity amplitude when two interfaces of the welding part are not combined.

If the chromaticity amplitude of a certain region (first region) is within the first chromaticity amplitude range, it represents that it is likely to be a welding region corresponding to a welding portion, and if the chromaticity amplitude of a certain region (second region) is within the second chromaticity amplitude range, it represents that it is likely to be a region corresponding to an unwelded portion. And the first chroma amplitude range is smaller than the second chroma amplitude range.

In the ultrasonic colorimetric image, a first region is selected, where the chromaticity amplitude is distributed in each point within the first chromaticity amplitude range, that is, a region which is likely to be a welding region is selected, and corresponding to fig. 2, the region W1 and the region W may be selected as the first region. Since the outside of the welding region H necessarily surrounds the unwelded region in the actual ultrasonic colorimetric image, the welding region H can be accurately selected in the ultrasonic colorimetric image by using the first region W1 surrounded by the second region S as the welding region H. That is, the first region W1 around the second region S is defined as the welding region H.

In fact, different bonding states of the interface can be distinguished by obvious boundary lines of different sound wave reflection energies of the welding area and the non-welding area around the welding area, so that the actual welding area is selected and judged.

In a specific implementation, for example, the first chroma threshold may be 100, the actual penetration value corresponding to the first chroma threshold may be 50 μm, and when the number of points in the welding region is 120, the first preset number may be 80. In other words, if the number of the points with the chromaticity amplitude smaller than 100 is greater than 80 out of 200 points included in the welding area, that is, the number of the points with the penetration reaching the standard in the welding area reaches a certain degree, it can be determined that the welding quality of the welding area is qualified.

Here, the first chromaticity threshold value and the first preset number are not limited to 100 and 80 described above, the first chromaticity threshold value may be obtained by experiments, and the first preset number may be determined according to the difference of the parts to be welded and the actually required size of the welding area, etc.

In some embodiments of the present application, if the number of points, of which the chromaticity amplitude is smaller than the first chromaticity threshold, in the points included in the welding area is greater than a first preset number, it is determined that the welding quality of the welding portion is qualified, and the method further includes:

calculating the area value of the welding area, and acquiring the average value of the chromaticity amplitude of each point in the welding area:

the area value of the welding area is outside a first preset range;

Compared with the prior art, the welding quality is different by reflecting the welding quality through a metallographic structure or a contact resistance and the like through a single parameter and means, in the embodiment, the welding quality is judged through two parameters, namely the chromaticity amplitude average value of the welding area and the chromaticity amplitude average value of the welding area, the welding quality can be judged to be unqualified as long as one of the parameters does not meet the requirement, the judgment is more accurate, and the possible condition of missed inspection is avoided.

The first preset range and the second preset range may be obtained through a previous experiment or simulation. The first preset range is the range of the corresponding welding area value when the welding quality of the welding part is qualified, and the second preset range is the average value of the chromaticity amplitude value of the corresponding welding area when the welding quality of the welding part is qualified. Here, the second preset range may be included in the first chrominance magnitude range.

The first preset range and the second preset range are ranges obtained in advance through experiments and researches of the inventor of the application, and if the ranges are met, the welding quality of the welding part can be judged to be qualified, so that the judgment mode is accurate and simple.

The average value of the chromaticity amplitude of each point in the welding region H can be obtained by averaging the chromaticity amplitudes of each point in the welding region H in the ultrasonic chromaticity image.

In some embodiments of the present application, acquiring an ultrasonic colorimetric image of a to-be-detected portion specifically includes:

acquiring an ultrasonic signal reflected by a part to be detected; and generating an ultrasonic chrominance image of the part to be detected according to the ultrasonic signal.

In some embodiments of the present application, before acquiring the ultrasonic signal reflected by the to-be-detected portion, the method further includes:

coating a coupling agent on a part to be detected; and attaching the ultrasonic probe to the part to be detected coated with the coupling agent, and controlling the ultrasonic probe to send ultrasonic waves to the welding part.

The welding quality detection method according to the embodiment of the present application is described below with reference to a specific example.

The embodiment of the present application will be described by taking welding of a tab and a post in a battery cell as an example. It can be understood that the application scenario of the welding quality detection method of the present embodiment includes, but is not limited to, welding between the interposer and the pole, and may also be applied to welding structures of other components.

Fig. 4 is a schematic structural diagram of a portion to be detected in a welding quality detection method according to some embodiments of the present application.

Referring to fig. 4, the battery cell 200 includes a top cap 230, a casing 240, and a battery cell (not shown), wherein a receiving space for receiving the battery cell is defined between the top cap 230 and the casing 240, and the battery cell is received in the receiving space. The tab (not shown) on the battery cell is electrically connected to the pole 210 provided on the top cap 230 through the adaptor sheet 220. The welding quality detection method of the embodiment of the present application is applied to detection of the welding quality of the welding portion between the rotating lug 220 and the pole 210.

In addition, the ultrasonic probe 110 is configured to emit an ultrasonic wave to a portion to be detected including the welding portion 250, and the ultrasonic receiver 120 is configured to receive an ultrasonic signal reflected from the portion to be detected and generate an ultrasonic colorimetric image of the portion to be detected from the ultrasonic signal. The ultrasonic probe 110 and the ultrasonic receiver 120 are electrically connected by a wire 140.

Fig. 5 is a schematic structural diagram of an interposer to be tested in a method for testing welding quality according to some embodiments of the present application, and fig. 6 is a schematic diagram of an ultrasonic chromaticity image obtained for the interposer of fig. 5.

Fig. 7 is a schematic structural diagram of another interposer to be tested in the method for testing solder quality according to some embodiments of the present application, and fig. 8 is a schematic diagram of an ultrasonic chromaticity image obtained for the interposer of fig. 7.

When the method for detecting the welding quality of the welding part is implemented, the method can comprise the following steps:

after the adapter sheet 220 and the pole 210 are welded, the exposed end surface of the pole 210 is coated with a volatile couplant, then the ultrasonic probe 110 is attached to the top of the pole 210, the ultrasonic probe 110 sends out an ultrasonic signal, and the received ultrasonic signal is converted into an ultrasonic chromaticity image by the ultrasonic receiver 120.

It should be noted that in the ultrasonic image, the darker the color, i.e. the greater the chromaticity, indicates that the energy transmittance at the position is poor, and the reflected signal is strong, which indicates that the welding effect at the position is poor, and the interface bonding is defective or even not bonded; on the contrary, the lighter the color is, the better the energy permeability is, the reflected signal is weak, which shows that the welding effect is good, the interface bonding is firm and no defect is generated.

In addition, different bonding states of the interface can cause distinct boundary lines to be distinguished due to different sound wave reflection energies of the welding area and the non-welding area, so that the welding area H can be selected from the ultrasonic chromaticity image, and the area of the welding area in the actual welding part 250 can be judged (in the welding quality evaluation of the interposer 220, the welding penetration and the welding area are both required).

The soldering of the interposer and the post in fig. 5 and fig. 7 is taken as an example for explanation. For convenience of illustration, the interposer in fig. 5 is defined as a first interposer 221, and the interposer in fig. 7 is defined as a second interposer 222.

As shown in fig. 5, the actual welding effect is shown when the welding area H1 is a circle with a radius of 1.5cm and the welding energy is 700w in the first transfer plate 221; fig. 6 is an ultrasonic chromaticity image acquired in the first switching piece 221 of fig. 5.

As shown in fig. 7, in the second interposer 222, the welding area H2 is a circle with a radius of 2cm, and the actual welding effect is 1400 w; fig. 8 is an ultrasonic colorimetric image acquired in the second interposer 222 of fig. 7.

Referring to fig. 5, the first switching sheet 221 is welded at a low power of 700W, a circle with a radius of 1.5cm is drawn, and from the ultrasonic detection result of fig. 6, it can be seen that in the welding region, the color is relatively light, and a part of the region has a dark color cluster, indicating that the energy permeability of the welding region H1 is general, and when a part of the region is not fully bonded, the fusion depth is not all greater than or equal to 100 um; the non-welded region S1 is highly energy reflective, with the feedback darker colored interface completely unbonded (penetration = 0). The welding region H1 can be easily selected because a distinct boundary exists between the color of the welding region H1 and the color of the non-welding region S1. Among the points included in the welding region H1, the number of points having a chromaticity amplitude smaller than 100 does not reach 66.7%, that is, if the number of points included in the welding region H1 is 100 parts and the number of points having a chromaticity amplitude smaller than 100 does not reach 66.7 parts, it is determined that the welding quality is not good. The welding power is low, so that the penetration is reduced, and the detection result of the welding region H1 is consistent with the actual welding condition, namely, the penetration is unqualified, and the welding quality is judged to be unqualified.

As shown in FIG. 8, when the welding power is increased to 1400W and the radius of the circle is increased to 2cm, it can be seen from FIG. 7 that as the welding radius is increased, the area with lighter color, i.e. the area of the welding region H2, is increased, and the color is lighter than that of the welding region H1 of FIG. 6, the interface is fully bonded, and the penetration is equal to or greater than 100 um.

Among the points included in the welding region H2, the number of points having a chromaticity amplitude smaller than 100 is greater than 66.7%, that is, if the number of points included in the welding region H2 is 100 and the number of points having a chromaticity amplitude smaller than 100 is greater than 66.7, it is determined that the welding quality is acceptable. This indicates that the interface bonding is better while the area of the welding region H2 is increased in the above welding quality detection method, in accordance with the actual welding situation.

In a second aspect, some embodiments of the present application provide a method of controlling a welding device, the method comprising:

judging the welding quality of the welding part by using the welding quality detection method of the embodiment;

Further, if it is judged that the welding quality of the welding portion is acceptable, the welding operation of the welding mechanism 510 in the welding apparatus is continued.

It is to be understood that the weld quality detection method has been described in detail above and will not be described in detail herein.

In some embodiments of the present application, in the welding quality detection method, if an absolute value of a difference between the number of points, of which the chromaticity amplitude is smaller than the first chromaticity threshold, and the first preset number is smaller than a second preset number, of the points included in the welding region, the welding of the welding mechanism is stopped, and the welding quality of the welding portion is detected by using a metallographic cutting method.

In the above method, if the absolute value of the difference between the number of points having a chromaticity amplitude smaller than the first chromaticity threshold and the first preset number is smaller than the second preset number, where the second preset number may be a smaller value, for example, in the case where the first preset number is 100, the second preset number may be 2, which means that the number of points having a chromaticity amplitude smaller than the first chromaticity threshold is located near the first preset number, it is proved that a welding quality failure may occur, and at this time, the welding operation of the welding mechanism may be stopped, and the welding quality of the welding portion may be detected by using other means, for example, a metallographic cutting method, so as to eliminate the welding quality problem that may occur, and thus the detection of the welding quality is more reliable.

Fig. 9 is a schematic structural diagram of a welding quality detection apparatus according to some embodiments of the present application.

In a third aspect, referring to fig. 9, some embodiments of the present application provide a welding quality detection apparatus 300, including:

a first obtaining module 310, configured to obtain an ultrasonic chromaticity image of a to-be-detected portion including a welding portion, where different chromaticities correspond to different interface bonding degrees in the ultrasonic chromaticity image; and

a selecting module 321, configured to select a welding region in the ultrasonic chromaticity image;

a second obtaining module 322, configured to obtain chromaticity amplitude values of points included in the welding region; and

the determining module 323 determines that the welding quality of the welding portion is qualified if the number of the points, of which the chromaticity amplitude is smaller than the first chromaticity threshold, is greater than a first preset number among the points included in the welding region.

In the above scheme, the first obtaining module 310 obtains the ultrasonic chromaticity image of the part to be detected, and the ultrasonic chromaticity image is used to judge the welding quality of the welding part, and the whole process does not need to damage the welding part and is directed to the nondestructive detection of the welding part, so that 100% full detection of the welding quality can be achieved. In addition, only the ultrasonic image of the part to be detected is required to be acquired, the part to be detected does not need to be cut or connected to a circuit for detection like the prior art, and therefore the detection efficiency is high. On the other hand, in the ultrasonic chromaticity image, different chromaticities correspond to different interface combination degrees respectively, so that the interface combination degree of a welding part can be reflected through the difference of the chromaticities in the image, namely, the welding quality is reflected, and the detection of the welding quality is accurate.

The selection module 321 selects the welding area and obtains the chromaticity amplitude of each point in the welding area, where the chromaticity amplitude of each point in the welding area is used to represent the welding quality, and the size of the welding area and the penetration of the welding area are considered, so as to more accurately reflect the quality of the welding quality.

In the above scheme, the first chroma threshold and the first preset number are ranges obtained in advance through experiments and research by the inventor of the present application, and the smaller the chroma amplitude, the smaller the penetration data of the point is, the better the welding quality is, therefore, if the number of the points of which the chroma amplitude is smaller than the first chroma threshold is greater than the first preset number, that is, the number of the points of which the penetration reaches the standard in the welding area reaches a certain degree, it can be determined that the welding quality of the welding area is qualified, and the determination method is accurate and simple.

In some embodiments of the present application, the selecting module 321 is specifically configured to:

and taking a first area surrounded by a second area as a welding area, wherein the second area is an area distributed by each point with chromaticity amplitude values within a second chromaticity amplitude value range, and the first chromaticity amplitude value range is smaller than the second chromaticity amplitude value range.

Since the bonding degree between two different interfaces in the region around the welding region is significantly different compared to the welding region, the difference is reflected in the ultrasonic chromaticity image, and a significant boundary is displayed in the image due to the significant size difference of the chromaticity amplitude. The first region can thus be used as a welding region by finding such a first region which is distinguishable from the surrounding second region by the chrominance amplitude.

In some embodiments of the present application, the determining module 323 is further specifically configured to: calculating the area value of the welding area and obtaining the average value of the chromaticity amplitude of each point in the welding area; and if at least one of the following conditions is met, determining that the welding quality of the welding part is unqualified:

the area value of the welding area is outside a first preset range;

Like this, the judging module 323 judges the welding quality through two parameters, namely the average value of the chromaticity amplitude of the welding area or the welding area, and can judge that the welding quality is unqualified as long as one of the parameters does not meet the requirement, so that the judgment is more accurate, and the possible condition of missing detection is avoided.

In some embodiments of the present application, the first obtaining module 310 is specifically configured to: acquiring an ultrasonic signal reflected by a part to be detected; and generating an ultrasonic chrominance image of the part to be detected according to the ultrasonic signal.

In a fourth aspect, some embodiments of the present application further provide a welding quality detection apparatus 400.

Fig. 10 is a schematic structural diagram of another structure of a welding quality detection apparatus according to some embodiments of the present application.

Referring to fig. 10, the welding quality detecting apparatus 400 includes:

an ultrasonic probe 110 for emitting ultrasonic waves to a portion to be detected including a welding portion;

an ultrasonic receiver 120 for receiving the ultrasonic signal reflected from the part to be detected and generating an ultrasonic colorimetric image of the part to be detected from the ultrasonic signal; and

and a processor 410 electrically connected with the ultrasonic receiver 120, wherein the processor 410 is used for judging the welding quality of the welding position according to the ultrasonic chromaticity image.

The processor 410 is specifically configured to: selecting a welding area in the ultrasonic chromaticity image;

obtaining the chromaticity amplitude of each point in the welding area;

In the above solution, similarly to the above, in the above solution, the ultrasonic probe 110 emits ultrasonic waves to the part to be detected, the ultrasonic receiver 120 is configured to receive ultrasonic signals reflected by the part to be detected and generate an ultrasonic colorimetric image, and the processor 410 determines the welding quality of the welding part by using the ultrasonic colorimetric image, wherein the whole process is a nondestructive test for the welding part without damaging the welding part, so that 100% of the total inspection of the welding quality can be achieved. In addition, only the ultrasonic image of the part to be detected is required to be acquired, the part to be detected does not need to be cut or connected to a circuit for detection like the prior art, and therefore the detection efficiency is high. On the other hand, in the ultrasonic chromaticity image, different chromaticities respectively correspond to different interface combination degrees, so that the interface combination degree of a welding part can be reflected through the difference of the chromaticities in the image, namely, the welding quality is reflected, and the welding quality is more accurately detected

In some embodiments of the present application, the processor 410 is further specifically configured to:

The processor 410 is specifically configured to:

the area value of the welding area is outside a first preset range;

In some embodiments of the present application, the processor 410 is further specifically configured to: acquiring an ultrasonic signal reflected by a part to be detected; and generating an ultrasonic chrominance image of the part to be detected according to the ultrasonic signal.

In some embodiments of the present application, the detection device further comprises a display 420, the display 420 is electrically connected to the ultrasonic receiver 120, and the display 420 is used for displaying the ultrasonic colorimetric image. Therefore, the interface bonding condition of the welding part can be conveniently and visually observed by an operator.

Alternatively, in some other embodiments, the display 420 may be electrically coupled to the processor 410 such that the processor 410 may receive the ultrasonic colorimetric image generated by the ultrasonic receiver 120 and display the ultrasonic colorimetric image on the display 420.

In a fifth aspect, some embodiments of the present application further provide a welding device 500, including:

a welding mechanism 510; and a welding quality detection device, which may be the welding quality detection device 300 or the welding quality detection device 400 in the foregoing embodiments. The welding mechanism 510 may be a mechanism for welding different parts, and may be, for example, a laser welding mechanism 510.

It is understood that the details, structure, principle, operation, etc. of the welding quality detecting apparatus 300 or the welding quality detecting apparatus 400 have been described in detail previously, and will not be described herein again.

In some embodiments of the present application, the welding device 500 further comprises a controller 520, the controller 520 being electrically connected to the processor 410;

the controller 520 is configured to control the welding mechanism 510 to stop the welding operation when the processor 410 determines that the welding quality at the welding site is not satisfactory.

If the processor 410 determines that the welding quality of the welding portion is not satisfactory, there is a possibility that the welding mechanism 510 fails, and at this time, if the controller 520 controls the welding mechanism 510 to stop the welding operation, it is possible to avoid the occurrence of a situation where a large number of non-satisfactory cells are produced.

In a sixth aspect, some embodiments of the present application provide a welding quality detection apparatus, including a memory and a processor, where the memory stores a computer program, and the processor implements the welding quality detection method and the steps of the control method of the welding apparatus when executing the computer program, where the implementation principle and the technical effect are similar, and are not described herein again.

In a seventh aspect, some embodiments of the present application provide a computer-readable storage medium, on which a computer program is stored, where the computer program is executed by a processor to implement the foregoing welding quality detection method and the foregoing steps of the control method of the welding apparatus, and the implementation principle and technical effects are similar, which are not described herein again.

In an eighth aspect, some embodiments of the present application provide a computer program product, which includes a computer program, and the computer program is executed by a processor to implement the foregoing welding quality detection method and the foregoing steps of the control method of the welding apparatus, and the implementation principle and the technical effect are similar, and are not described herein again.

All possible combinations of the technical features of the above embodiments may not be described for the sake of brevity, but should be considered as within the scope of the present disclosure as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A welding quality detection method for detecting welding quality of a welding site, characterized by comprising:

acquiring an ultrasonic chromaticity image of a part to be detected including the welding part, wherein different chromaticities correspond to different interface bonding degrees respectively in the ultrasonic chromaticity image;

selecting a welding area in the ultrasonic chromaticity image;

obtaining the chromaticity amplitude of each point in the welding area;

and if the number of points of which the chromaticity amplitude is smaller than a first chromaticity threshold value in the points included in the welding area is larger than a first preset number, judging that the welding quality of the welding part is qualified.

2. The welding quality detection method according to claim 1, wherein the selecting a welding area in the ultrasonic chromaticity image specifically includes:

selecting a first area in the ultrasonic chromaticity image, wherein the first area is an area distributed by each point of which the chromaticity amplitude is located in a first chromaticity amplitude range;

and taking the first area surrounded by a second area as the welding area, wherein the second area is an area distributed by points of which the chromaticity amplitude is within a second chromaticity amplitude range, and the first chromaticity amplitude range is smaller than the second chromaticity amplitude range.

3. The welding quality detection method according to claim 2, wherein if the number of points having a chromaticity amplitude smaller than a first chromaticity threshold among the points included in the welding region is larger than a first preset number, it is determined that the welding quality of the welding portion is acceptable, and the method further comprises:

calculating the area value of the welding area, and obtaining the average value of the chromaticity amplitude of each point in the welding area;

the area value of the welding area is positioned outside a first preset range;

4. The welding quality detection method according to any one of claims 1 to 3, wherein the acquiring of the ultrasonic colorimetric image of the portion to be detected including the welding portion specifically includes:

acquiring an ultrasonic signal reflected by a part to be detected;

and generating an ultrasonic chromaticity image of the part to be detected according to the ultrasonic signal.

5. The welding quality detection method according to claim 4, wherein before acquiring the ultrasonic signal reflected by the portion to be detected, the method further comprises:

coating a coupling agent on the part to be detected;

and attaching an ultrasonic probe to the part to be detected coated with the coupling agent, and controlling the ultrasonic probe to send ultrasonic waves to the welding part.

6. A control method of a welding apparatus, comprising:

judging the welding quality of the welding portion by using the welding quality detection method according to any one of claims 1 to 5;

7. A welding quality detection device, characterized by comprising:

the ultrasonic chromaticity image acquisition device comprises a first acquisition module, a second acquisition module and a processing module, wherein the first acquisition module is used for acquiring an ultrasonic chromaticity image of a part to be detected including a welding part, and different chromaticities in the ultrasonic chromaticity image respectively correspond to different interface combination degrees; and

a second obtaining module, configured to obtain chromaticity amplitude values of points included in the welding region; and

and the judging module is used for judging that the welding quality of the welding part is qualified if the number of the points of which the chromaticity amplitude is smaller than a first chromaticity threshold value is larger than a first preset number in all the points included in the welding region.

8. The welding quality detection device according to claim 7, wherein the selection module is specifically configured to:

9. The welding quality detection device of claim 7, wherein the determination module is specifically configured to:

the area value of the welding area is positioned outside a first preset range;

10. The welding quality detection device according to any one of claims 7 to 9, wherein the first acquisition module is specifically configured to:

acquiring an ultrasonic signal reflected by a part to be detected;

11. A welding quality detection device, characterized by comprising:

an ultrasonic probe (110) for emitting ultrasonic waves to a site to be inspected including a weld site;

the ultrasonic receiver (120) is used for receiving the ultrasonic signal reflected by the part to be detected and generating an ultrasonic chromaticity image of the part to be detected from the ultrasonic signal; and

a processor (410) electrically connected to the ultrasonic receiver (120), the processor (410) for selecting a weld region in the ultrasonic colorimetric image;

obtaining the chromaticity amplitude of each point in the welding area;

12. The weld quality detection apparatus according to claim 11, wherein the processor (410) is further configured to:

calculating the area value of the welding area, and obtaining the average value of the chromaticity amplitude of each point in the welding area; and if at least one of the following conditions is met, determining that the welding quality of the welding part is unqualified:

the area value of the welding area is outside a first preset range;

13. The weld quality detection device according to claim 11 or 12, wherein the weld quality detection device (400) further comprises a display (420), the display (420) is electrically connected to the ultrasonic receiver (120), and the display (420) is used for displaying the ultrasonic colorimetric image.

14. A welding device, comprising:

a welding mechanism (510); and

a welding quality detection device according to any one of claims 7 to 10 and 11 to 13.

15. The welding device according to claim 14, wherein when the welding quality detection device is according to any one of claims 11 to 13, the welding device (500) further comprises a controller (520), the controller (520) being electrically connected to a processor (410) in the welding quality detection device;

the controller (520) is configured to control the welding mechanism (510) to stop the welding operation when the processor (410) determines that the welding quality of the welding site is not acceptable.

16. A weld quality detection apparatus comprising a memory and a processor, the memory storing a computer program, wherein the processor, when executing the computer program, implements the steps of the method of any one of claims 1 to 5.