diff --git a/frontend/src/views/Material.vue b/frontend/src/views/Material.vue
index d026fa2..5b9a9a5 100644
--- a/frontend/src/views/Material.vue
+++ b/frontend/src/views/Material.vue
@@ -654,14 +654,15 @@ export default {
     },
     tick() {
       this.now = Date.now()
-      this.weld.position = (this.weld.position + 0.012) % 1
-      // 新一卷开始时滚动卷号
-      if (this.weld.position < 0.012) {
-        this.prev_coil_no = this.current.coil_no
-        const n = parseInt(this.current.coil_no || '26053552', 10) + 1
-        this.current.coil_no = String(n)
+      // 焊缝(带头)位置与线速度跟随实际在产卷进度（带头 = run_length / 2000）
+      const pp = this.producingPlan
+      if (pp) {
+        this.weld.position = Math.max(0, Math.min(1, this.prodLength / 2000))
+        this.current.speed = pp.run_speed || 0
+      } else {
+        this.weld.position = 0
+        this.current.speed = 0
       }
-      this.current.speed = Math.max(0, rnd(this.current.speed, 4))
 
       const wig = (o, key, amp) => { o[key] = rnd(o[key], amp) }
       wig(this.uncoiler, 'tension', 0.4); wig(this.uncoiler, 'speed', 2)