KR101221052B1 - Resistance spot welding method - Google Patents
Resistance spot welding method Download PDFInfo
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- KR101221052B1 KR101221052B1 KR1020100114958A KR20100114958A KR101221052B1 KR 101221052 B1 KR101221052 B1 KR 101221052B1 KR 1020100114958 A KR1020100114958 A KR 1020100114958A KR 20100114958 A KR20100114958 A KR 20100114958A KR 101221052 B1 KR101221052 B1 KR 101221052B1
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Abstract
The present invention relates to a resistance spot welding method.
In the resistance spot welding method according to the present invention, the initial input step of setting and inputting the pressing force applied to the welding plate and the target welding current output to the welding plate, and starting the supply of the input current for outputting the target welding current to start welding Welding execution step for performing a, current measurement step for measuring the actual welding current output to the welding plate material according to the supply of the input current, current comparison step for comparing the actual welding current and the target welding current and the actual welding current Is a feedback control step of controlling feedback so that the actual welding current is equal to the target welding current when the target welding current is different from the target welding current.
According to the present invention, the welding quality can be prevented to greatly improve the welding quality.
Description
The present invention relates to a resistance spot welding method. More specifically, the present invention relates to a resistance point welding method that can prevent the flying phenomenon to improve the welding quality.
Electrical resistance welding is a method in which welding materials are brought into contact with each other while applying an appropriate pressure to energize them when they are heated by heat generated by contact resistance and specific resistance of the metal itself. Lap welding can be classified.
Resistance spot welding is a welding which performs point joining of a plate, and is a kind of overlap welding.
1 is a view for explaining the basic principle of the resistance spot welding, Figure 2 is a view for explaining the flow of heat and resistance to the nugget (nugget) by the resistance heating in the resistance spot welding.
Referring to FIGS. 1 and 2, resistance spot welding is welding by resistance heat generated by energizing two sheets of plates (
In the process of performing the resistance spot welding, if the heat input amount is not properly controlled, the melt, that is, the nugget is scattered (expulsion) occurs, the problem that the welding quality is deteriorated.
In particular, in the conventional process of performing a DC resistance point welding process of high strength steel, in order to increase the quality of the welded part, the heat input amount is excessively welded in general. In this case, the blowing phenomenon occurs more frequently due to excessive heat input, and thus there is a problem that a welding defect occurs.
The present invention is to provide a resistance point welding method that can prevent the flying phenomenon to improve the welding quality.
More specifically, the present invention, in particular, by controlling the welding current to control the amount of heat supplied to the welding site in order to minimize the occurrence of flying phenomenon that occurs frequently during the resistance point welding process for high strength steel, It is a technical problem to minimize and greatly improve the welding quality.
In the resistance point welding method according to the present invention for solving this problem, an initial input step of setting and inputting a pressing force applied to a welding plate and a target welding current output to the welding plate, an input current for outputting the target welding current. A welding execution step of starting a supply by performing a welding operation, a current measurement step of measuring an actual welding current output to the welding plate member according to the supply of the input current, and comparing a current comparing the actual welding current with the target welding current And a feedback control step of controlling feedback so that the actual welding current is equal to the target welding current when the actual welding current is different from the target welding current.
Between the initial input step and the welding execution step, it is characterized in that it further comprises a current waveform setting / input step of setting and inputting the waveform of the input current.
In the current waveform setting / input step, a ratio of a heating time at which the input current maintains a high level to a cooling time at a low level is set and input.
The input current has a pulse waveform, and a heating time of a unit pulse constituting the input current is 10 ms or more and 50 ms or less, and a cooling time of the unit pulse is 1 ms or more and 20 ms or less.
In the initial input step, characterized in that additionally set the welding termination condition to input.
After the current comparison step, if the actual welding current is the target welding current, characterized in that it further comprises a welding end condition determination step for determining whether the welding end condition is satisfied.
The welding end condition is characterized in that the welding time set by the user.
In the feedback control step, the actual welding current is controlled to be equal to the target welding current by a proportional integral differential (PID) control method.
According to the present invention, there is an effect that the resistance point welding method that can improve the welding quality by preventing the flying phenomenon.
More specifically, in order to minimize the occurrence of flying phenomena due to excessive heat input that occurs frequently during resistance spot welding of high strength steel, the welding current is controlled to stably control the heat input supplied to the welding portion, It has the effect of minimizing the generation and greatly improving the welding quality.
1 is a view for explaining the basic principle of resistance spot welding.
FIG. 2 is a view for explaining the flow of heat and diffusion of a nugget, which is a welded portion, by resistance heating in resistance spot welding.
3 is a view showing a resistance point welding method according to an embodiment of the present invention.
4 is a view conceptually showing an example of a device configuration for performing a resistance point welding method according to an embodiment of the present invention of FIG.
FIG. 5 is a photograph photographing a change of a nugget, which is a welded portion that appears according to a welding current, according to an embodiment of the present invention.
6 is a diagram illustrating a current supply system for supplying current to a welding site according to an embodiment of the present invention.
7 is a view conceptually illustrating an example of a welding current control waveform according to an embodiment of the present invention.
8 is a view illustrating a comparison of a conventional welding current waveform and a welding current control waveform applied to an embodiment of the present invention.
9 and 10 are conceptual views illustrating other examples of the welding current control waveform according to an embodiment of the present invention.
11 is a photograph photographing a comparison of welded areas when a conventional method and an embodiment of the present invention are applied.
12 is a photograph photographing a comparison of an actual welding operation site when a conventional method and an embodiment of the present invention are applied.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
3 is a view showing a resistance point welding method according to an embodiment of the present invention, Figure 4 conceptually shows an example of an apparatus configuration for performing a resistance point welding method according to an embodiment of the present invention of FIG. Drawing.
3 and 4, the resistance point welding method according to an embodiment of the present invention is the initial input step (S10), current waveform setting / input step (S20), welding execution step (S30), current measurement step ( S40), a current comparison step S50, a feedback control step S60, and a welding termination condition determination step S70.
<Initial input step (S10)>
In the initial input step (S10), the user performs a process of setting and input the pressing force applied to the weld plate material and the target welding current output to the weld plate material.
The target welding current is the current that is finally output to the welding plate through the process of transformer, rectification, etc., and the user sets and inputs this target welding current under specific welding conditions such as the material or thickness of the welding plate. In FIG. 5, according to an embodiment of the present disclosure, a photograph of a change of a nugget, which is a welding portion appearing according to a welding current, is disclosed.
The pressing force is a physical force applied to the
In this initial input step (S10), the user can additionally set and input the welding termination condition, this welding termination condition may be a welding time set in advance by the user.
<Current waveform setting / input step (S20)>
In the current waveform setting / input step S20, a process of setting and inputting a waveform of an input current is performed. For example, the current waveform setting / input step S20 may be executed between the initial input step S10 and the welding execution step S30, and the heating time at which the input current maintains the high level and the cooling at the low level are maintained. The method may be performed by setting and inputting a ratio of time.
For example, when the input current has a pulse waveform, the heating time of the unit pulse constituting the input current is adjusted within a range of 10 ms to 50 ms, and the cooling time of the unit pulse is within a range of 1 ms to 20 ms. It is desirable to adjust. If the heating time is less than 10ms, the amount of heat input to the welding site is insufficient, and if the heating time is more than 50ms, excessive heat input is applied to the welding site, causing the melt to blow out. The range of cooling time is the value computed in consideration of this range of heating time.
This will be described in more detail with reference to FIG. 6, which shows the overall current supply system.
FIG. 6 is a diagram illustrating an overall current supply system for supplying current to a welding site according to one embodiment of the present invention.
Referring to FIG. 6, first, the waveform control circuit converts a waveform of an input current according to a waveform setting command set and input by a user and outputs the waveform of the input current to the gate driver. The waveform of the welding current output to the welding portion has a waveform corresponding to the waveform of this input current.
Next, the PWM inverter outputs a pulse width modulated signal, that is, primary current, to the transformer according to the gate control signal output from the gate driver.
The secondary current output from the transformer is finally converted into a welding current through a rectifier and output.
7 is a view conceptually illustrating an example of a conventional welding current waveform and a welding current control waveform according to an embodiment of the present invention, and FIG. 8 is a conventional welding current waveform and a welding current control applied to an embodiment of the present invention. It is the figure which showed the concrete comparison with a waveform. Referring to FIGS. 7 and 8, it can be seen that the waveform controlled according to the present exemplary embodiment has a heating time for maintaining a high level and a cooling time for maintaining a low level, unlike the conventional case.
In this embodiment, in addition to the rectangular pulse as disclosed in FIG. 7, a triangular wave pulse shown in FIG. 9 or a pulse having any shape as shown in FIG. 10 may be applied as the welding current.
As such, if the waveform of the welding current has a pulse shape and the duty ratio of the pulse is controlled, the welding current can be continuously supplied during the welding process, and unlike the conventional case, the melt flow of the melt is prevented. It can prevent.
<Welding execution step (S30)>
In the welding execution step (S30), a process of starting the supply of the input current for outputting the target welding current and performing the welding is performed. The input current is calculated by the target welding current set by the user. More specifically, when the user inputs the desired target welding current through the input means provided in the welder, based on the variables such as the transformer ratio of the transformer included in the system for supplying current in logic provided in the welder. The input current for outputting the target welding current is automatically calculated.
More specifically, in the welding execution step (S30), by applying a pressing force to the electrode in contact with the welding plate material, by supplying a welding current to the electrode, generates a heat of resistance to generate a nugget melted between the welding plate material to weld plate material To be welded.
<Current Measurement Step (S40)>
In the current measuring step (S40), a process of measuring the actual welding current output to the welding plate member in accordance with the supply of the input current is performed.
Since the magnitude of the actual welding current is very large, it is preferable to measure the signal after performing a signal conversion process using, for example, a pressure reducing circuit and an insulating element (not shown).
<Current comparison step (S50)>
In the current comparing step S50, a process of comparing the actual welding current with the target welding current is performed.
As a result of the comparison in the current comparison step (S50), 1) when the actual welding current is different from the target welding current, it is switched to a feedback control step (S60) to be described later, and 2) when the actual welding current is the same as the target welding current, the welding described later It is switched to the end condition determination step (S70).
<Feedback Control Step (S60)>
In the feedback control step S60, when the actual welding current is different from the target welding current, a feedback control process is performed such that the actual welding current is equal to the target welding current.
For example, in the feedback control step S60, the actual welding current may be controlled to be equal to the target welding current by a proportional integral differential control method.
When the feedback control is performed by the proportional integral control method, the error value between the target to be controlled, that is, the actual welding current measured in the current measuring step S40 and the target welding current set in the initial input step S10, is calculated. Using this error value, the control value required for the control is calculated, and the control value is used to control the actual welding current to be equal to the target welding current using this control value.
<Welding termination condition determination step (S70)>
In the welding termination condition determination step (S70), when the actual welding current is equal to the target welding current, a process of determining whether the welding termination condition is satisfied is performed.
This welding end condition can be set and input in the initial input step (S10). In addition, the welding termination condition may be a welding time preset by the user.
The welding process may be forcibly terminated by the user in addition to being terminated by meeting a preset welding end condition.
FIG. 11 is a photograph photographing a comparison of welded areas when a conventional method and an embodiment of the present invention are applied, and FIG. 12 is a comparative photograph of actual welding performance sites when the conventional method and an embodiment of the present invention are applied. One picture.
Referring to FIGS. 11 and 12, unlike the conventional case, according to the present exemplary embodiment, the flying phenomenon is minimized and the welding quality is greatly improved.
According to the present invention as described in detail above, there is an effect that the resistance point welding method that can improve the welding quality by preventing the flying phenomenon.
More specifically, in order to minimize the occurrence of flying phenomena due to excessive heat input that occurs frequently during resistance spot welding of high strength steel, the welding current is controlled to stably control the heat input supplied to the welding portion, It has the effect of minimizing the generation and greatly improving the welding quality.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. In addition, it is obvious that any person skilled in the art may make various modifications and imitations without departing from the scope of the technical idea of the present invention.
S10: initial input stage
S20: Current waveform setting / input step
S30: Welding Run Step
S40: current measurement step
S50: current comparison step
S60: feedback control step
S70: determination of welding termination condition
Claims (8)
An initial input step of setting and inputting a pressing force applied to the welding plate member and a target welding current outputted to the welding plate member;
A welding execution step of performing welding by starting supply of an input current for outputting the target welding current;
A current measuring step of measuring an actual welding current output to the welding plate member according to the supply of the input current;
A current comparing step of comparing the actual welding current with the target welding current; And
And a feedback control step of controlling feedback so that the actual welding current is equal to the target welding current when the actual welding current is different from the target welding current.
And a current waveform setting / input step for setting and inputting a waveform of the input current between the initial input step and the welding execution step.
And in the current waveform setting / input step, input by setting a ratio between a heating time at which the input current maintains a high level and a cooling time at a low level.
The input current has a pulse waveform, the heating time of the unit pulse constituting the input current is 10ms or more and 50ms or less, and the cooling time of the unit pulse is 1ms or more and 20ms or less, resistance point welding method.
In the initial input step, characterized in that additionally set the welding termination condition, the resistance point welding method.
And a welding end condition determination step of determining whether the welding end condition is satisfied when the actual welding current is equal to the target welding current after the current comparison step.
The welding termination condition is a resistance point welding method, characterized in that the preset welding time by the user.
In the feedback control step, the resistance welding method characterized in that for controlling the actual welding current to be equal to the target welding current by a proportional integral differential (PID) control method.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020100114958A KR101221052B1 (en) | 2010-11-18 | 2010-11-18 | Resistance spot welding method |
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| KR1020100114958A KR101221052B1 (en) | 2010-11-18 | 2010-11-18 | Resistance spot welding method |
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| KR20120053704A KR20120053704A (en) | 2012-05-29 |
| KR101221052B1 true KR101221052B1 (en) | 2013-01-10 |
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| KR1020100114958A KR101221052B1 (en) | 2010-11-18 | 2010-11-18 | Resistance spot welding method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20230128189A (en) | 2022-02-25 | 2023-09-04 | 동의대학교 산학협력단 | Resistance Spot Weld Softening Heat Treatment Method for Mechanical Fastening |
| KR20230146698A (en) | 2022-04-12 | 2023-10-20 | 동의대학교 산학협력단 | Single Side Resistance Element Welding Method |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100225256B1 (en) | 1997-04-15 | 1999-10-15 | 조재철 | The apparatus with auto-control input heating quantity in high wave spot welder and the control method of the same |
| KR100263534B1 (en) | 1997-12-31 | 2000-08-01 | 추호석 | Method of controlling welding power in welding robot |
| KR20060104769A (en) * | 2005-03-31 | 2006-10-09 | 장희석 | Appartus for micro spot welding using an accelerometer and control method thereof |
| KR20100117746A (en) * | 2009-04-27 | 2010-11-04 | 에스케이에너지 주식회사 | Device and method for controlling resistance welding in lithium secondary battery |
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2010
- 2010-11-18 KR KR1020100114958A patent/KR101221052B1/en active IP Right Grant
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100225256B1 (en) | 1997-04-15 | 1999-10-15 | 조재철 | The apparatus with auto-control input heating quantity in high wave spot welder and the control method of the same |
| KR100263534B1 (en) | 1997-12-31 | 2000-08-01 | 추호석 | Method of controlling welding power in welding robot |
| KR20060104769A (en) * | 2005-03-31 | 2006-10-09 | 장희석 | Appartus for micro spot welding using an accelerometer and control method thereof |
| KR20100117746A (en) * | 2009-04-27 | 2010-11-04 | 에스케이에너지 주식회사 | Device and method for controlling resistance welding in lithium secondary battery |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20230128189A (en) | 2022-02-25 | 2023-09-04 | 동의대학교 산학협력단 | Resistance Spot Weld Softening Heat Treatment Method for Mechanical Fastening |
| KR20230146698A (en) | 2022-04-12 | 2023-10-20 | 동의대학교 산학협력단 | Single Side Resistance Element Welding Method |
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| KR20120053704A (en) | 2012-05-29 |
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