current starts to decrease with a dropping slope K1. Because of
thermal inertia, the keyhole volume remains to expand slowly
even though both heat input and arc force associated with the
welding current start to drop during this stage. At instant t3, when
the keyhole size reaches the pre-set value to meet the desired
practical requirements of weld quality, the current decreases at a
steeper slope K2 (|K2|
>
|K1|), so that the keyhole stops expanding
but starts to close. At instant t4, the keyhole is completely closed,
and the efflux plasma voltage is zero. The current is switched to
base level IB at instant t5. After IB is applied for a pre-selected
period TB = t6 −
t5, the current is switched to the peak level IP
again to begin a new cycle. In this way, it can ensure the keyhole
establishing and full penetration but avoid burn-through defects.
To characterize the keyhole size and weld bead width at backside
of the workpiece, the average value (VEP) of efflux plasma
voltage (VE) from t2 to t3 in each cycle is used as the feedback signal
because it has been validated that the measured VEP is well
correlated with the weld bead width at backside of the workpiece
[28]. Take the average value of efflux plasma voltage (VEP) as the
controlled variable. Take the pulse current value (IP) and its two
dropping slopes (K1 and K2) as the controlling variables. Through
adjusting IP and K1 & K2, keep VEP within the preselected range so
that the weld penetration and weld bead width is controlled. The
PI (proportional and integral) controller is used to adjust IP and K1
& K2 according to the difference between the measured VEP and
setpoint ¯VEP .
To test the control effectiveness of the developed control system
further, a test plate with varied thickness is used, as shown in
Fig. 25. Because the plate thickness is gradually varied from 8 mm
to 4 mm, the welding process cannot maintain consistence if no
appropriate control action is applied. By employing the developed
system, the peak current and both its duration and dropping slopes
are able to make suitable adjustment based on the measured efflux
plasma voltage signal as the thickness varies along the welding
direction. Fig. 26 is the photograph of the weld appearance at both
topside and backside. It looks that the weld formation and penetration
are controlled very well, even if the plate thickness changes
so much.
To optimize this process variant-controlled pulse keyholing
PAW, theoretical and experimental work has been conducted to
current starts to decrease with a dropping slope K1. Because of
thermal inertia, the keyhole volume remains to expand slowly
even though both heat input and arc force associated with the
welding current start to drop during this stage. At instant t3, when
the keyhole size reaches the pre-set value to meet the desired
practical requirements of weld quality, the current decreases at a
steeper slope K2 (|K2|
>
|K1|), so that the keyhole stops expanding
but starts to close. At instant t4, the keyhole is completely closed,
and the efflux plasma voltage is zero. The current is switched to
base level IB at instant t5. After IB is applied for a pre-selected
period TB = t6 −
t5, the current is switched to the peak level IP
again to begin a new cycle. In this way, it can ensure the keyhole
establishing and full penetration but avoid burn-through defects.
To characterize the keyhole size and weld bead width at backside
of the workpiece, the average value (VEP) of efflux plasma
voltage (VE) from t2 to t3 in each cycle is used as the feedback signal
because it has been validated that the measured VEP is well
correlated with the weld bead width at backside of the workpiece
[28]. Take the average value of efflux plasma voltage (VEP) as the
controlled variable. Take the pulse current value (IP) and its two
dropping slopes (K1 and K2) as the controlling variables. Through
adjusting IP and K1 & K2, keep VEP within the preselected range so
that the weld penetration and weld bead width is controlled. The
PI (proportional and integral) controller is used to adjust IP and K1
& K2 according to the difference between the measured VEP and
setpoint ¯VEP .
To test the control effectiveness of the developed control system
further, a test plate with varied thickness is used, as shown in
Fig. 25. Because the plate thickness is gradually varied from 8 mm
to 4 mm, the welding process cannot maintain consistence if no
appropriate control action is applied. By employing the developed
system, the peak current and both its duration and dropping slopes
are able to make suitable adjustment based on the measured efflux
plasma voltage signal as the thickness varies along the welding
direction. Fig. 26 is the photograph of the weld appearance at both
topside and backside. It looks that the weld formation and penetration
are controlled very well, even if the plate thickness changes
so much.
To optimize this process variant-controlled pulse keyholing
PAW, theoretical and experimental work has been conducted to
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current starts to decrease with a dropping slope K1. Because of
thermal inertia, the keyhole volume remains to expand slowly
even though both heat input and arc force associated with the
welding current start to drop during this stage. At instant t3, when
the keyhole size reaches the pre-set value to meet the desired
practical requirements of weld quality, the current decreases at a
ความลาดชัน ( | K2 K2 |
>
| K1 | ) เพื่อให้ดาวเทียมหยุดขยาย
แต่เริ่มที่จะปิด ที่ T4 ทันที , keyhole สมบูรณ์ปิด
และการผลักดันพลาสมาแรงดันศูนย์ ปัจจุบันจะเปลี่ยนไป
ระดับฐาน IB ที่ 5 ทันที หลังจาก IB ใช้สำหรับก่อนเลือกระยะเวลา TB = −
T6 T5 ในปัจจุบันเปลี่ยนไป ระดับ สูงสุด IP
อีกครั้งเพื่อเริ่มวงจรใหม่ ในวิธีนี้มันสามารถตรวจสอบการสร้างและการเจาะรูกุญแจ
เต็ม แต่หลีกเลี่ยงการเผาผ่านข้อบกพร่อง .
ลักษณะและรูกุญแจขนาดกว้างที่เชื่อมลูกปัดด้านหลัง
ของชิ้นงาน ค่าเฉลี่ย ( vep ) ของการพลาสมา
แรงดัน ( ได้ ) จาก T2 T3 ในแต่ละรอบเพื่อใช้เป็นสัญญาณ
เพราะมีความคิดเห็น ถูกตรวจสอบว่าได้เป็นอย่างดี
vepcorrelated with the weld bead width at backside of the workpiece
[28]. Take the average value of efflux plasma voltage (VEP) as the
controlled variable. Take the pulse current value (IP) and its two
dropping slopes (K1 and K2) as the controlling variables. Through
adjusting IP and K1 & K2, keep VEP within the preselected range so
that the weld penetration and weld bead width is controlled. The
PI (proportional and integral) controller is used to adjust IP and K1
& K2 according to the difference between the measured VEP and
setpoint ¯VEP .
To test the control effectiveness of the developed control system
further, a test plate with varied thickness is used, as shown in
Fig. 25. Because the plate thickness is gradually varied from 8 mm
to 4 mm,งานเชื่อมกระบวนการรักษาความมั่นคงไม่ได้ ถ้าไม่ควบคุมการกระทำ
เหมาะสมใช้ . โดยใช้ระบบพัฒนา
, สูงสุดในปัจจุบัน และทั้งระยะเวลาและการลาด
สามารถปรับให้เหมาะสมตามวัดแรงดันสัญญาณ เช่น การ
พลาสมาความหนาแตกต่างกันไปตามแนวเชื่อม
ทิศทาง 26 รูปที่เป็นภาพถ่ายในลักษณะที่เชื่อมทั้ง
ด้านบน และด้านหลัง ดูที่เชื่อมการก่อตัวและการเจาะ
ถูกควบคุมอย่างดี ถ้าความหนาของแผ่น
การเปลี่ยนแปลงมาก เพื่อเพิ่มประสิทธิภาพกระบวนการนี้ตัวแปรควบคุมชีพจร keyholing
อุ้งเชิงทฤษฎีและทดลองใช้งานได้
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