Adjustment method:
First loosen the two fastening screws of the thread trimming cam, and align the engraved point on the upper wheel (according to the line) with the engraved point on the casing. Then push the bobbin brake to the left until the bobbin is stopped. Use your right hand to turn the thread trimming cam so that the bobbin thread front knife roller enters the curved groove on the thread trimming cam. Continue to rotate in the same direction as the lower shaft. Rotate the cam until it stops, then tighten the first and second screws in sequence.
The amount of loosening of the second thread clamping plate when pushing the bobbin brake lever to the right with your left hand, then the second thread clamping plate will automatically loosen, and the amount of loosening is Within 0.5~1MM, when trimming the thread, if the clamping plate of the second thread clamp is not loosened, the upper thread will easily come off the needle. If it is kept loosened, a floating thread will be produced, which means that the thread clamping is completely invalid. Adjust To increase the loosening amount, just loosen nut B and rotate nut A. On the contrary, just loosen nut A and tighten nut B.
The function and adjustment of the bobbin brake lever. The elbow of the bobbin brake lever is equipped with a sliding sleeve, which is riveted by a small spring inside. The bobbin brake relies on the elastic force of the small spring to make the bobbin stop. When trimming the thread, the bobbin will not reverse due to the tension of the thread. If the brake is too tight, the bottom thread will be cut too short, because the bobbin will not rotate at all due to the brake being too tight, and the bottom thread will be too short. If it is short, it will also cause off-line phenomenon. On the contrary, if the brake is extremely loose, the upper thread wound around the bobbin brake lever will slip off the lever during thread trimming, and the thread on the needle will be very short, causing the needle to fall off, so it must be adjusted correctly.
Screwing the screw in and out will change the position of the limit block. Adjust until the end of the sliding sleeve on the brake lever just touches the bobbin and the other end touches the engraved line on the brake lever.
After careful research on the cooperation and coordination of various mechanisms on the sewing machine, the Heavy Machinery Company not only invented and patented the rotating disc thread take-up mechanism in the 1950s, but also carried out detailed research on the main mechanisms of the sewing machine. movement was studied.
When the needle bar is at the uppermost point, the thread take-up lever is still taking up the thread. This is regarded as the zero position of motion (0°).
2. When the spindle rotates 64°, the thread take-up rod reaches the highest point, the standard is between 60°~70°.
3. When the needle reaches 1 mm from the plane of the needle plate (that is, when punching cloth), it is 100°.
4. When the needle tip reaches the needle plate plane, it is 116°.
5.325° and 15° are the entry and exit times of the pivot baffle respectively.