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熱成型板的普及使用也促使熱成型板的焊接技術要跟上潮流，下邊簡單介紹下熱成型板的點焊工藝技術方法與流程-RSJ!

本文涉及一種適用于使用超高強度鋼的汽車白車身結構強度焊接的方法，用于完成了車身GEO定位焊后增加車身結構強度的白車身點焊，屬于汽車制造技術領域。 

背景技術：

隨著對汽車安全、節能等要求的提升，基于固溶強化、沉淀強化、細化晶粒、位錯強化和相變強化(馬氏體)的超高強度鋼進入了實際生產應用階段。為了提高和滿足碰撞安全性能并提高車身部件強度，超高強度熱成型剛點焊性能和技術的重要性就凸顯了出來。

傳統的汽車白車身使用的是鍍鋅板，兩層鍍鋅板焊接時，使用鐵屑進行夾緊定位。由于高強度熱成型鋼本身的材料特性，熱成型鋼白車身的焊接技術需要更強的焊接壓力、更長的焊接時間和能量，故傳統的定位銷無法滿足高強度的夾具定位需求，其耐磨性和強度都達不到工藝要求，無法滿足焊接尺寸和固定定位尺寸精度的要求。在不滿足精度的環境情況下，如果兩層鋼板直接搭接和預壓會出現空隙或者出現在非規劃的位置焊接的情況，對汽車整體的產品質量和結構強度有著較大的影響。

技術實現要素：

 本發明要解決的技術問題是如何對超高強度鋼的汽車白車身進行定位和點焊。

為了解決上述技術問題，本發明的技術方案是提供一種熱成型鋼白車身點焊方法，其特征在于，步驟為：

步驟1：將熱成型鋼汽車白車身的兩層鋼板的焊接面相互貼合； 

步驟2：將所述兩層鋼板通過陶瓷定位銷夾緊定位；

步驟3：在所述兩層鋼板上待點焊處外側分別設置一電極帽；

 步驟4：給兩個電極帽之間施加焊接電流和焊接壓力，使得所述兩層鋼板上待點焊處熔融并固化成焊接接頭。

優選地，所述電極帽經過了用于提高硬度的熱處理工藝。

優選地，所述步驟4中，焊點剪切強度位移≤5s/mm。

優選地，所述步驟4中，電極縮進量一致性≥97％。

優選地，所述步驟4中，當兩層鋼板中的薄板厚度為0.75～1mm時，焊接壓力為3.9～4.3KN，焊接時間為330～440ms，焊接電流為10～12ms，電極帽直徑為16mm。

優選地，所述步驟4中，當兩層鋼板中的薄板厚度為1.1～2mm時，焊接壓力為4.4～6KN，焊接時間為460～660ms，焊接電流為12.5～15.5ms，電極帽直徑為16～20mm。 

優選地，所述步驟4中，焊接參數如表1所示：

表1 熱成型鋼焊接參數表

 表1中，板厚表示兩層鋼板中的薄板厚度，接觸面直徑表示電極帽端面與鋼板接觸面的直徑

相比現有技術，本發明具有如下有益效果：

1、配套熱成型鋼的使用，電極帽采用高硬度熱處理，提高配套夾具整體精度和耐磨使用壽命；

2、采用陶瓷銷作為夾具的定位，有著彎曲強度高和電絕緣的特點，安全，且能減少后續清理焊渣的工作量； 

3、采用新焊接工藝參數和高強度配套夾具的模式，提高產品一次合格率，提高了生產效率；

4、高精度焊接夾具的配套使用，從縮短工位停機時間入手，有效降低了焊裝車間的綜合成本；

5、首次將陶瓷定位銷和經高硬度熱處理工藝的電極帽壓塊引入熱成型鋼點焊領域，推進了焊接整體工藝的進步。

附圖說明

圖1為熱成型鋼白車身點焊時示意圖；

圖2為傳統板材和熱成型鋼焊接壓力與板厚關系對比圖；

圖3為傳統板材和熱成型鋼焊接時間與板厚關系對比圖；

圖4為傳統板材和熱成型鋼焊接電流與板厚關系對比圖。

具體實施方式

下面結合具體實施例，進一步闡述本發明。應理解，這些實施例僅用于說明本發明而不用于限制本發明的范圍。此外應理解，在閱讀了本發明講授的內容之后，本領域技術人員可以對本發明作各種改動或修改，這些等價形式同樣落于本申請所附權利要求書所限定的范圍。 

一種熱成型鋼白車身點焊方法，步驟為：

步驟1：將熱成型鋼汽車白車身的兩層鋼板的焊接面1相互貼合，如圖1所示；

步驟2：兩層鋼板通過陶瓷定位銷2夾緊定位；

 步驟3：兩層鋼板上待點焊處外側分別設置一電極帽3；電極帽3使用了高硬度熱處理工藝，以保證白車身焊接過程中尺寸的穩定性；

步驟4：給兩個電極帽3之間施加焊接電流和焊接壓力，使得兩層鋼板上待點焊處熔融并固化成焊接接頭。 

陶瓷定位銷的技術指標如下：

1)超強的耐磨性：

壓縮強度(MPa)：2300

彎曲強度(MPa)：240

彈性比率(GPa)：280

2)防粘附性：可以有效減少焊渣，灰塵的附著；

3)電絕緣：滿足沃爾沃嚴格的全球絕緣技術規范要求；

4)高溫下的超高強度，耐熱性(℃)：1700

5)使用壽命超長：確保焊接工藝最小的廢品率以及最短的停機時間，有效降低焊裝車間的綜合成本。

本實施例所采用的陶瓷銷的型號有：D15-040960385(31915024)，D13-034422378(31915023)，D15-040962889(31553145)。

熱成型鋼點焊的技術指標如下：

1)點焊焊接速度：2s/點；

2)焊點剪切強度位移：≤5s/mm；

3)電極縮進量(熱成型鋼母材剩余厚度)一致性≥97％

4)焊槍的焊接壓力為普通鍍鋅板材的2倍。

對傳統的鍍鋅板和本發明熱成型鋼(硼鋼-Boron-Steel)進行多次實驗過程，并控制同樣板厚，以進行焊接參數的對比，從而實現焊接理論和實踐相結合，得出熱形成鋼白車身的焊接工藝參數設置規律，實現對熱成型剛車身焊接在實際生產工藝中的應用。根據點焊電阻參數標ES-6M2A-1K251-A*，電極參數根據ISO5821實施，針對碳鋼的層疊焊接、高強度涂層鋼的層疊焊接及合金板材GMT焊接進行焊接參數的實驗探索，實驗數據如下： 

表1 熱成型鋼焊接參數表

表2 傳統板材焊接參數表

 熱成型鋼與傳統板材焊接參數分別如表1和表2所示，傳統板材和熱成型鋼焊接壓力與板厚關系對比如圖1所示，傳統板材和熱成型鋼焊接時間與板厚關系對比如圖2所示，傳統板材和熱成型鋼焊接電流與板厚關系對比如圖3所示。

由上述數據可以看出：

一、焊接電流、電壓和焊接時間在熱成型鋼上的應用設置，根據板厚的不同，變化曲線及趨勢相對普通鍍鋅板幾乎一致；

二、熱成型鋼的白車身焊接壓力相比鍍鋅板起點壓力要求較高，隨著板厚的增加相比鍍鋅板的焊接壓力增幅從70％下降到30％左右；

 三、由于熱成型鋼細化晶粒、位錯強化和相變強化(馬氏體)的特點，焊接時間相比鍍鋅板的增幅在100％左右，需要更長的焊接保壓時間以熔穿鋼板，不足夠的焊接保壓時間在實驗中會造成虛焊或焊接強度不夠等各種質量欠缺的問題，故足夠的焊接時間針對熱成型剛是必須的；

 四、熱成型鋼的焊接電流，相比鍍鋅板相差無幾，即當焊接同板厚時所需的能量幾乎一致；

五、綜合比較熱成型鋼(硼鋼)的焊接參數，較傳統鍍鋅板在保持焊點尺寸和電極帽尺寸的情況下，各項焊接參數均需要提升30％～100％以滿足熱成型鋼的焊接需求。

 為配套熱成型鋼的使用，本發明創新性地利用陶瓷銷作為夾具的定位，并同時對電極帽壓塊使用了高硬度熱處理工藝，以保證白車身焊接過程中尺寸的穩定性，提高配套夾具整體精度和耐磨使用壽命。 

在工藝參數方面，通過不斷的測試和檢測焊接質量、焊接剪切強度位移及測試焊接后的電極縮進量等，將熱成型鋼的焊接電流、焊接壓力和焊接保壓時間等固化和保留下來，開創并建立了國內熱成型鋼白車身焊接的一套技術指標。 

通過陶瓷定位銷和焊接工藝參數的使用，不僅可以提高白車身的焊接定位精度，同時可以補全熱成型鋼白車身應用領域的實踐空白，為制定行業標準和提高焊接速率提供了基礎。

更多熱成型焊接技術詳情請聯系昆山榮仕杰！點擊本網站首頁觀看視頻資料。

英文版;

This paper relates to a method for strength welding of automobile body-in-white structure using ultra-high-strength steel. It is used to complete the body-in-white spot welding which increases the structural strength of the vehicle body after GEO welding. It belongs to the field of automobile manufacturing technology.



Background technique:

With the improvement of requirements for safety and energy saving of automobiles, ultra-high-strength steels based on solid solution strengthening, precipitation strengthening, grain refinement, dislocation strengthening and phase transformation strengthening (martensite) have entered the practical production application stage. In order to improve and meet crash safety performance and increase the strength of body parts, the importance of ultra-high strength thermoforming just spot welding performance and technology is highlighted.

The traditional car body-in-white uses a galvanized sheet, and when the two-layer galvanized sheet is welded, it is clamped and positioned using iron filings. Due to the material properties of high-strength thermoformed steel, the welding technology of thermoformed steel body-in-white requires stronger welding pressure, longer welding time and energy, so the traditional positioning pin can not meet the high-strength fixture positioning requirements. The wear and strength are not up to the process requirements, and the welding size and the fixed positioning dimensional accuracy cannot be met. In the case of an environment that does not meet the accuracy, if the two layers of steel plates are directly overlapped and pre-stressed, there will be voids or welding in an unplanned position, which has a great influence on the overall product quality and structural strength of the automobile.



Technical realization elements:

The technical problem to be solved by the present invention is how to position and spot weld the automobile white body of ultra high strength steel.

In order to solve the above technical problem, the technical solution of the present invention is to provide a hot-formed steel body-in-white spot welding method, characterized in that the steps are:

Step 1: bonding the welding faces of the two layers of steel plates of the hot-formed steel automobile body-in-white;

Step 2: clamping and positioning the two-layer steel plate through a ceramic positioning pin;

Step 3: respectively, an electrode cap is respectively disposed on the outer side of the two-layer steel plate to be spot-welded;

Step 4: Apply welding current and welding pressure between the two electrode caps, so that the spot welding on the two steel plates is melted and solidified into a welded joint.

Preferably, the electrode cap is subjected to a heat treatment process for increasing hardness.

Preferably, in the step 4, the joint shear strength displacement is ≤5 s/mm.

Preferably, in the step 4, the electrode retraction amount is consistent by ≥97%.

Preferably, in the step 4, when the thickness of the thin plate in the two-layer steel plate is 0.75 to 1 mm, the welding pressure is 3.9 to 4.3 KN, the welding time is 330 to 440 ms, the welding current is 10 to 12 ms, and the electrode cap diameter is 16 mm. .

Preferably, in the step 4, when the thickness of the thin plate in the two-layer steel plate is 1.1 to 2 mm, the welding pressure is 4.4 to 6 KN, the welding time is 460 to 660 ms, the welding current is 12.5 to 15.5 ms, and the electrode cap diameter is 16 ~20mm.

Preferably, in the step 4, the welding parameters are as shown in Table 1:

Table 1 Thermoforming steel welding parameters table

In Table 1, the plate thickness indicates the thickness of the thin plate in the two-layer steel plate, and the diameter of the contact surface indicates the diameter of the contact face of the electrode cap and the steel plate.

Compared with the prior art, the present invention has the following beneficial effects:

1. The use of matching thermoformed steel, the electrode cap adopts high hardness heat treatment to improve the overall precision and wear life of the supporting fixture;

2. The ceramic pin is used as the positioning of the fixture, which has the characteristics of high bending strength and electrical insulation, is safe, and can reduce the workload of subsequent cleaning of the welding slag;

3. Adopt new welding process parameters and high-strength supporting fixture mode to improve the first pass rate of products and improve production efficiency;

4. The matching use of high-precision welding fixtures starts with shortening the station downtime, which effectively reduces the comprehensive cost of the welding shop;

5. For the first time, ceramic locating pins and electrode cap briquettes with high hardness heat treatment process were introduced into the field of thermoforming steel spot welding, which promoted the progress of the overall welding process.

DRAWINGS

Figure 1 is a schematic view of a hot-formed steel body-in-white spot welding;

Figure 2 is a comparison diagram of the relationship between the welding pressure and the plate thickness of the conventional sheet and the thermoformed steel;

Figure 3 is a comparison diagram of the relationship between welding time and plate thickness of conventional sheet and thermoformed steel;

Figure 4 is a comparison of welding current and plate thickness of conventional sheet and thermoformed steel.

detailed description

The invention is further illustrated below in conjunction with specific embodiments. It is to be understood that the examples are not intended to limit the scope of the invention. In addition, it should be understood that various changes and modifications may be made by those skilled in the art in the form of the present invention.

A hot-formed steel body-in-white spot welding method, the steps are:

Step 1: bonding the welding faces 1 of the two-layer steel plate of the hot-formed steel automobile body-in-white to each other, as shown in FIG. 1;

Step 2: The two-layer steel plate is clamped and positioned by the ceramic positioning pin 2;

Step 3: an electrode cap 3 is respectively disposed on the outer side of the two-layer steel plate to be spot-welded; the electrode cap 3 uses a high-hardness heat treatment process to ensure dimensional stability during the body-in-white welding process;

Step 4: Apply welding current and welding pressure between the two electrode caps 3, so that the spot welding on the two steel plates is melted and solidified into a welded joint.

The technical specifications of ceramic positioning pins are as follows:

1) Superior wear resistance:

Compressive strength (MPa): 2300

Bending strength (MPa): 240

Elastic ratio (GPa): 280

2) Anti-adhesion: It can effectively reduce the adhesion of welding slag and dust;

3) Electrical insulation: meet Volvo's strict global insulation technical specifications;

4) Ultra high strength at high temperature, heat resistance (°C): 1700

5) Long service life: ensuring the lowest scrap rate and the shortest downtime of the welding process, effectively reducing the overall cost of the welding shop.

The types of ceramic pins used in this embodiment are: D15-040960385 (31915024), D13-034422378 (31915023), D15-040962889 (31553145).

The technical specifications of hot-formed steel spot welding are as follows:

1) Spot welding speed: 2s/point;

2) Welding point shear strength displacement: ≤ 5s / mm;

3) The amount of electrode indentation (residual thickness of thermoformed steel base material) is ≥97%

4) The welding pressure of the welding torch is twice that of ordinary galvanized sheet.

The traditional galvanized sheet and the hot-formed steel (Boron-Steel) of the present invention were subjected to a plurality of experimental processes, and the same thickness was controlled to compare the welding parameters, thereby realizing the combination of welding theory and practice. The welding process parameter setting law of the hot-formed steel body-in-white is realized, and the application of the hot-formed body welding in the actual production process is realized. According to the spot welding resistance parameter standard ES-6M2A-1K251-A*, the electrode parameters are implemented according to ISO5821, and the experimental research on welding parameters of laminated welding of carbon steel, laminated welding of high-strength coated steel and GMT welding of alloy sheet, experimental data as follows:

Table 1 Thermoforming steel welding parameters table

Table 2 Traditional plate welding parameter table

The welding parameters of thermoformed steel and traditional plate are shown in Table 1 and Table 2. The relationship between welding pressure and plate thickness of traditional plate and thermoformed steel is shown in Figure 1. The relationship between welding time and plate thickness of traditional plate and thermoformed steel is For example, as shown in Figure 2, the relationship between welding current and plate thickness of conventional sheet and thermoformed steel is shown in Figure 3.

It can be seen from the above data:

First, the welding current, voltage and welding time on the hot-formed steel application settings, according to the thickness of the plate, the curve and trend is almost the same as ordinary galvanized sheet;

Second, the white body welding pressure of the hot-formed steel is higher than the starting pressure of the galvanized sheet. As the thickness increases, the welding pressure increase of the galvanized sheet decreases from 70% to about 30%;

Third, due to the characteristics of refinement grain, dislocation strengthening and phase transformation strengthening (martensite) of thermoformed steel, the welding time is about 100% higher than that of galvanized sheet, which requires a longer welding dwell time to melt Wearing steel plates, insufficient welding dwell time will cause various problems such as insufficient welding or insufficient welding strength in the experiment, so sufficient welding time is necessary for thermoforming;

Fourth, the welding current of the hot-formed steel is almost the same as that of the galvanized sheet, that is, the energy required for welding the same plate thickness is almost the same;

V. Comprehensive comparison of the welding parameters of hot-formed steel (boron steel). Compared with the traditional galvanized sheet, the welding parameters need to be increased by 30% to 100% to meet the hot-rolled steel. Welding requirements.

In order to support the use of thermoformed steel, the invention innovatively utilizes the ceramic pin as the positioning of the fixture, and at the same time uses a high hardness heat treatment process for the electrode cap compact to ensure dimensional stability during the body-in-white welding process and improve the supporting fixture. Overall accuracy and wear life.

In terms of process parameters, the welding current, welding pressure and welding holding time of the hot formed steel are solidified and retained by continuous testing and testing of welding quality, welding shear strength displacement and testing of electrode shrinkage after welding. Created and established a set of technical indicators for domestic thermoforming steel body-in-white welding.

Through the use of ceramic locating pins and welding process parameters, not only can the welding body positioning accuracy be improved, but also the practice gap in the field of hot-formed steel body-in-white can be complemented, which provides a basis for setting industry standards and increasing welding rate.

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