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真空钎焊炉日常故障及排除方法：
|
故障出现现象 |
故障产生的原因 |
真空钎焊炉故障排除解决方法 |
|
温度控制失灵 |
1、热电偶断丝
2、温控仪表故障 |
1、更换新的热电偶。
2、按温控仪表说明书进行检修。 |
|
真空钎焊炉达不到极限真空度或
抽空时间太长 |
1、真空钎焊炉真空系统故障
2、真空钎焊炉炉体泄漏、真空钎焊炉内换热器漏水。
3、真空计电阻规管、电离规管损坏 |
1、检查 排除 。
2 、检查真空钎焊炉内换热器。
3、更换真空计的规管。 |
|
升温功率达不到额定值 |
1、磁性调压器故障
2、石墨加热管污染，电阻值升高
3、新石墨管电阻率和调压器不匹配。 |
1、检修 磁性调压器 。
2、更换新石墨加热管。
3、检查石墨管电阻率。 |
|
处理零件表面不亮 |
1、冷却气体不纯
2、真空度太低 |
1、确保氮（氩）气纯度99.9996%以上。 含水量、含氧量小于5ppm
2、检查真空钎焊炉的真空系统、冷却系统。 |
|
热电偶烧毁 |
1、热电偶与碳毡相碰
2、热电偶不密封 |
1、排除真空钎焊炉加热器 。
2、检查密封圈。 |
|
绝缘电阻<1000欧 |
电极周围有碳纤维 |
清除飞铜、烘炉处理、清理碳纤维。 |
|
真空阀开关失灵 |
1、压缩空气压力不足
2、电磁阀故障（振动引起电磁体与
壳体相对运动 |
1、保证气压不小于0.5MPa 。
2、检修 、加橡胶垫压紧。 |
|
机械泵故障 |
1、不能起动
2、旋转方向反了
3、运转不灵活
4、抽气效率低
5、达不到真空度 |
1、检查电机起动器开关的位置和过载保护装置与冷却水开关 。
2、更换电机三相中的二相接线。
3、按说明书修理。
4、油污染、换新油，如无改变则检查真空系统其它部份。
5、排除油污染；更换轴端油封；打开镇气阀排空水分。 |
|
传动部件运行故障 |
限位失灵 |
把限位和行程开关撞击装置协调一致。 |
|
机械增压泵故障 |
1、不动作
2、异常噪音
3、达不到真空度 |
1、 检查电机起动器开关和过载保护器是否工作 。
2、 排除齿轮精度不够，转子动平衡不好；抽承偏摆误差或
损坏；联轴节不同轴。
3、 更换轴端密封，调整转子与转子，转子与定子，转子与
端盖的间隙。 |
真空钎焊炉定期维护表
厂内进行的
每天 1. 检查冷却塔和储水箱，按需要替换过滤器 。
2. 依次把粗抽泵油过滤器移到下一泵，按需要替换过滤器。
3. 检查粗抽泵油位和油温，听听机械上有无问题。
每周 1. 对全部真空炉做冷态泄露检查，最大0.5Pa/H
2. 检查扩散泵，罗茨泵和维持泵的油位
3. 给空气压缩机储气罐放气（水）
4.对所有真空炉控制系统进行检查
每月 1 .校验全部温度仪表
2. 替换控制箱内的全部空气过滤器
3. 给炉子的主阀门上机油和黄油
每三个月 1. 校验仪表的校正仪
2. 校验全部真空仪表
3. 替换热电偶进行检验
4. 真空炉9点均温性测试
半年： 1.氩气管路系统压力测试
2. 真空炉的热态泄露试验
3. 露点表校验，给真空泵换油
4. 替换粗抽泵油和活门
每年： 1. 检查并清刷全部配电柜电路板
2. 氩气纯度校验
3. 检查主变压器油位，替换粗抽泵油分离器
4. 校验试验各电电气仪表。
真空钎焊炉热电偶常见故障及处理
|
故障现象 |
可能原因 |
处理方法 |
|
热电势比实际值小（显示仪表指示值偏低） |
热电极短路 |
找出短路原因，如因潮湿所致，则需进行干燥；如因绝缘子损坏所致，则需更换绝缘子 |
|
热电偶的接线柱处积灰，造成短路 |
清扫真空钎焊炉内积灰 |
|
补偿导线线间短路 |
找出短路点，加强绝缘或更换补偿导线 |
|
热电偶热电极变质 |
在长度允许的发问下，剪去变质段重新焊接，或更换新热电偶 |
|
补偿导线与热电偶极性接反 |
重新接正确 |
|
补偿导线与热电偶不配套 |
更换相配套的补偿导线 |
|
热电偶安装位置不录或插入深度不符合要求 |
重新按规定安装热电偶 |
|
热电偶冷端温度补偿不符合要求 |
调整热电偶冷端补偿器 |
|
热电偶与显示仪表不配套 |
更抽热电偶或显示仪表使之相配套 |
|
热电势比实际值大（显示仪表指示值偏高） |
热电偶与显示仪表不配套 |
更抽热电偶或显示仪表使之相配套 |
|
补偿导线与热电偶不配套 |
更换补偿导线使之相配套 |
|
有直流干扰信号进入 |
排除直流干扰 |
|
热电势输出不稳定 |
热电偶接线柱与热电极接触不良 |
将接线柱螺丝拧紧 |
|
热电偶测量线路绝缘破损，引起断续短路或接地 |
找出故障点，修复绝缘 |
|
热电偶安装不牢或外部震动 |
紧固热电偶，消除震动或采取减震措施 |
|
热电极将断未断 |
修复或更换热电偶 |
|
外界干扰（交流漏电，电磁场感应等） |
查出干扰源，采用屏蔽措施 |
|
热电偶热电势误差大 | , ,
热电极变质
更换热电极 |
|
热电偶安装位置不当 |
改变安装位置 |
|
热电偶保护管表面积灰 |
清除积灰 |
真空钎焊炉压升率不合格
一、漏气
A、密封损坏漏气，优先检查真空钎焊炉门密封圈、电极密封圈、热电偶密封圈等接口密封圈，一般由水压欠造成真空钎焊炉密封圈受热老化。
B、真空钎焊炉壳焊缝开造成内漏或外漏，氩弧焊焊接质量差造成，如果是内漏用氦质谱检漏仪都检不出来。需要加压检漏。
C、联接的换热器漏，真空钎焊炉炉后部分换热器火焰焊接质量差造成，要对真空钎焊炉换热器单独检漏。
D、阀门漏气，真空钎焊炉常用对蝶阀、挡板阀、插板阀、球阀、电磁阀、薄膜, 阀等阀门，阀门的密封圈在不干净的环境中容易损坏密封圈，在有污染的环境中应该先用120号汽油清洗过滤网，在把阀和泵装配好。
二、真空钎焊炉内部材料放气
A、炉壳内壁，在南方天气比较潮湿，真空钎焊炉开炉门后时间长，真空炉内加热室吸潮之后，易造成漏气的假象。
B、保温隔热材料放气，真空钎焊炉用的隔热材料一般有金属、碳材料和陶瓷纤维，陶瓷纤维在低温保温效果好，但吸气特大，碳材料与次之。
C、真空钎焊炉里后冷却换热器表面放气，主要是因为换热器的翅片面积特别大，吸附气体之后还不容易放出来。
D、随炉钎焊工装夹具放气、待钎焊产品的材料放气、尤其是汽车EGR系统的产品ni基钎料装配以后产品没烘干就进真空钎焊炉。解决以上问题需要进行烘炉。但烘炉对换热器没有多大效果，需要在产品进真空钎焊炉前单独对产品烘干。真空钎焊炉需要在烘炉后充入气体，启动风机进行热风循环才可能解决。
D、虚焊放气及装配螺纹孔内放气，真空钎焊炉壳内壁焊接不好，石墨电极与铜电极没有留放气孔等，这个问题应该在设计制造时解决，实际使用中很难遇到。
三、仪表读数
A、这主要是针对国内真空钎焊炉的真空计，国内真空计的读数是将本来的对数关系使用了分段插值的分段直线关系，这会造成测试压升率时，一段合格一段不合格。
B、真空计使用的电阻规有效测量值是0.1~2500Pa，国内仪表每次使用前都要进行满度和零点的调整，如果没有没有调好，本来只有0.1Pa的变化可能变成1Pa的变化。
C、国外的真空记录仪没有国内的复杂，一般不需要调整，如果显示不准的话，一般可以在大气压下复位就可以。
D、如果设备上有好几种测量仪器，可以相互对照，麦氏计是一种绝对量的真空计，测量范围为0.1~500Pa，可以用麦氏计对电子真空计进行校准。
怎么测真空钎焊炉的压升率:
正确的测量方法是：烘炉完成之后，在干净、冷态、空载的状态下在t1到t2的时间段内测得真空度由P1到P2的两个值，压升率=P2-P1/t2-t1，P的单位为Pa，t的单位为小时，所以压升率的单位为Pa/h。我国的标准是1.33Pa/h，国外多是0.67Pa/h，因为要与国际接轨，现在国内压升率指标与多采用0.67Pa/h了。但国外的设备指标一般还考虑到设备的休积，所以取名为泄露率，单位为：Pa.L/S。
导致真空钎焊炉压升率不合格的可能原因:
1、密封损坏漏气，用丙酮优先检查真空钎焊炉门密封圈、电极密封圈、热电偶密封圈等接口密封圈，一般由水压欠造成真空钎焊炉密封圈受热老化。
2、真空钎焊炉壳焊缝开造成内漏或外漏，焊接质量差造成，如果是内漏用氦质谱检漏仪都检不出来。
3、联接的换热器漏，真空钎焊炉炉后部分换热器焊接质量差造成，要对真空钎焊炉换热器单独检漏。
4、阀门漏气，真空钎焊炉常用对蝶阀、挡板阀、插板阀、球阀、电磁阀、薄膜阀等阀门，阀门的密封圈在不干净的环境中容易损坏密封圈，在有污染的环境中应该先用120号汽油清洗阀和泵在进行装配，并且烘干。
东俊真空钎焊工作室
地址:江苏省扬州市维扬路349号
邮政编码：225000
联系人： 蔡东俊
SKYPE:jsyzcdj
联系手机：13905275926
QQ：649200691
MSN：jsyzcdj@126.com
E-mail: jsyzcdj@126.com
网址：http://www.brazing.com.cn
新加坡联系地址：10 Anson Road #05-17
联系人： Feng Guo An
联系电话:+65-6756 3629
手机：+0065-6756 3629
传 真: +0065-6754 8382
电子邮件：fengga@el.sg
德国联系地址： Ringenkuhler Straße 26
34298 Helsa
联系人：李向珍
联系电话: 004956049180277
手机： 004956049180277
传 真: 004956049180278
电子邮件info@china-market-expertise.de
Vacuum brazing furnace daily failure and troubleshooting methods:
|
Failure phenomenon |
Causes of the failure |
Troubleshooting solution of vacuum brazing furnace |
|
Temperature control Failure |
1、Thermocouple broken wire
2、Temper, ature control instrument failure |
1、Replace the new thermocouple
2、According to the temperature control instrument manual maintenance |
|
The vacuum brazing furnace does not reach the ultimate vacuum or time is too long |
1、vacuum brazing furnace vacuum system failure
2、Vacuum brazing furnace body leakage, vacuum brazing furnace heat exchanger leakage.
3、 The vacuum gauge resistance gauge and the ionization gauge damage
|
1、Check, Exclude
2 、Check the vacuum brazing furnace heat exchanger
3、Replace the regulation of the vacuum gauge |
|
The heating power does not reach the rated value |
1、Magnetic voltage regulator failure
2、Graphite heating tube pollution, resistance increased
3、The new graphite tube resistivity does not match. |
1、Maintenance of magnetic voltage regulator
2、Replace the new graphite heating tube
3、Check the graphite tube resistivity |
|
The surface of the processing part is not bright |
1、The cooling gas is not pure
2、the vacuum is too low |
1、 to ensure that nitrogen (argon) gas purity of more than 99.9996%. Water content, oxygen content less than 5ppm
2、Check the vacuum system and cooling system of vacuum brazing furnace. |
|
Thermocouple burned down |
1、thermocouple and carbon felt touch
2、thermocouple is not sealed |
1、Excluding vacuum brazing furnace heater
2、Check the sealing ring
|
|
Insulation resistance<1000 Ω
|
The electrodes are surrounded by carbon fibers |
Remove the fly copper, oven treatment, clean up the carbon fiber |
|
Vacuum valve switch failure |
Compressed air pressure is insufficient
2、Solenoid valve Failure (Vibration caused by the relative movement of the electromagnet and the shell)
|
1、 Ensure that air pressure is not less than 0.5 MPa
2、Maintenance, plus rubber pad and tighten |
|
Mechanical pump failure |
1、Can not start
2、 The direction of rotation reversed
3、The operation is not flexible
4、Low pumping efficiency
5、Can not reach the degree of vacuum |
1、Check the motor starter switch position and overload protection device and cooling water switch
2、Replace the two phase wiring in the motor three phase
3、Repair according to the instructions
4、Oil pollution, for new oil, if no change to check the other parts of the vacuum system.
5、The exclusion of oil pollution; replace shaft end oil seal；open the gas ballast valve |
|
The transmission parts Running fault |
Limit failure |
Put the limit and impact devices in harmony |
|
Mechanical booster pump failure |
1、No action
2、Abnormal noise
3、Not reach the degree of vacuum |
1、Check whether the motor starter switch and overload protector work
2、 Eliminate the gear accuracy is not enough, the rotor dynamic balance is not good; bearing deflection error or damage; coupling different shafts
3、 , Re, pl, ac, e , th, e , sh, af, t , se, al, , , ad, ju, st the r, otor and rotor, rotor and stator, rotor and end cover gap |
,
Common Faults and Treatment of Thermocouple in Vacuum Brazing Furnace
|
Failure phenomenon |
Possible causes |
Processing method |
|
The thermoelectric potential is smaller than the actual value (display instrument indication value is low) |
Thermal electrode short circuit |
To find out the cause of short circuit, such as due to moisture，it needs to be dry; If the insulator is damaged, the insulator must be replaced. |
|
The junction of the thermocouple is accumulated dust, causing a short circuit |
Cleaning of dust in vacuum brazing furnace |
|
Short circuit between compensation conductor line |
Find the short circuit point, strengthen insulation or replace compensating wires |
|
Thermocouple thermal electrode metamorphism |
In the range of allowable length, cut off the metamorphic section re-welding, or replace the new thermocouple |
|
The compensation conductor wire is reversed with the thermocouple polarity |
Re-connect correctly |
|
Compensation wire and thermocouple are not matched |
Replace the matching compensation wire |
|
Thermocouple installation location is incorrect or insertion depth does not meet requirements |
Re-install Thermocouples as required |
|
Thermocouple cold junction temperature compensation does not meet the requirements |
Adjust the thermocouple cold junction compensator |
|
Thermocouple and display instruments are not matched |
Replace thermocouple or display instrument to make it match |
|
The thermoelectric potential is larger than the actual value (display instrument indication value is high) |
Thermocouple and display instruments are not matched |
Replace thermocouple or display instrument to make it match |
|
Compensation wire and thermocouple are not matched |
Replace the matching compensation wire |
|
There is a DC interference signal to enter |
Eliminate DC interference |
|
Thermoelectric output is unstable |
Compensating conductor is in poor contact with the hot electrode |
Tighten the terminal screws |
|
Thermocouple measuring line insulation damage, causing intermittent short circuit or grounding |
Find fault points and repair insulation |
|
Thermocouple installation is not strong or external vibration |
Tighten the thermocouple, eliminate vibration or take shock measures |
|
The thermal electrode will be broken |
Repair or replace thermocouple |
|
External disturbance (AC leakage, electromagnetic induction, etc.) |
Detection of interference sources, the use of shielding measures |
|
Large error of thermocouple thermoelectric potential |
Thermoelectrode metamorphism |
Replace the hot electrode |
|
Improper installation position of Thermocouple |
Change the installation location |
|
Thermocouple protection tube surface dust |
Clear dust |
Vacuum brazing furnace pressure rise rate unqualified
First, the Leak
A. Seal damage leakage, priority check vacuum brazing door seal ring, electrode seal ring, thermocouple sealing ring and other interface seals, generally by water pressure due to vacuum brazing furnace sealing ring aging.
B. Vacuum brazing furnace shell welding cracks resulting in internal leakage or external leakage, poor welding quality caused, If it's an internal leak, it's not detectable by helium mass leak detector.
C. Connection heat exchanger leakage, caused by poor welding quality of heat exchanger in the latter part of vacuum brazing furnace. Need to separate leak detection for vacuum brazing furnace heat exchanger.
D. Valve leakage,vacuum brazing furnace commonly used butterfly valve, baffle valve, flashboard valve, ball valve, solenoid valves, membrane valves and other valves, the valve seal ring in the dirty environment is easy to damage, in a polluted environment should be filtered and then into the valve and pump.
Second, the vacuum brazing furnace internal material deflated
A. The inner wall of the shell, in the south more humid weather, moisture absorption, easy to cause leakage of the illusion.
B. Thermal insulation materials deflated, vacuum brazing furnace insulation is generally metal, carbon materials and ceramic fiber, ceramic fiber in low-temperature insulation effect is good, but inspiratory large,carbon material and second.
C. Vacuum brazing furnace heat exchanger deflation, mainly because the heat exchanger fin area is particularly large, adsorption gas is not easy to release.
D. With the furnace brazing fixture deflated, to be brazed product material deflated, especially the car EGR system products Ni-based solder assembly after the product did not dry into the vacuum brazing furnace.To solve the above problems need to bake oven. But the bake oven does not have much effect on the heat exchanger, and needs to be dried separately before the product enters the vacuum brazing furnace. The vacuum brazing furnace needs to be filled with gas after the oven, start the fan for hot air circulation can be resolved.
E. Virtual welding deflated and assembly threaded hole is deflated, vacuum brazing furnace shell inner wall welding is bad, graphite electrode and the copper electrode did not leave a vent hole, etc., this problem should be solved during design and manufacture, it's hard to meet in practical use.
Third, the instrument readings
A. This is mainly for the domestic vacuum brazing furnace vacuum gauge, the domestic vacuum gauge reading is the original logarithmic relationship using the segmentation of the interpolation of the linear relationship between the line, which will result in test pressure rise rate, a section of qualified and a section of unqualified.
B. Vacuum gauge used resistance gauge effective measurement value is 0.1 ~ 2500 Pa, the domestic instrument should be used before the full and zero adjustment, if there is no tune, had only 0.1Pa changes may become 1Pa changes.
C. The foreign vacuum recorder measurement is not complicated and generally does not need to be adjusted, and if the display is not allowed, generally can be reset at atmospheric pressure can be.
D. If there are several measuring instruments on the device, they can be compared with each other, McLeod gauge is an absolute amount of vacuum gauge with a measuring range of 0.1~500PA, you can use McLeod gauge to calibrate the electronic vacuum gauge.
Regular maintenance table for vacuum brazing furnaces
In the factory
|
Day |
1.Check the cooling tower and the storage tank and replace the filter as needed |
2.Move the coarse pump oil filter to the next pump in turn ,replace the filter as needed |
3.Check the crude pump oil level and oil temperature, listen to the mechanical problems |
|
Weekly |
1. All vacuum furnace to do cold leakage inspection, the maximum 0.5Pa / H |
2.Check diffusion pump, roots pump and maintain pump oil level |
3.air compressor release air |
4.Check all vacuum furnace control systems |
|
Monthly |
1.Check all temperature instruments |
2.Replace all air filters in the control cabinet |
3.Put the oil and butter on the main valve of the furnace |
|
Every three months |
1.Calibration instrument for calibration instrument |
2.Check all vacuum instruments |
3.Replace the thermocouple for inspection |
4.Vacuum furnace temperature uniformity test |
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Six months |
1.Argon p, , , , , , , ip, eline sys, tem pressure test |
2.Vacuum furnace thermal leakage test |
3. Check the dew point meter, change oil for vacuum pump |
4. Replace the crude pump oil and the valve |
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1. Check and brush all circuit boards |
2. Argon Purity Calibration |
3.Check the main transformer oil level, replace the crude pump oil separator |
4.Calibration test of each meter |
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