Analysis of common failures of worm gear box parts of post-printing paper cutter

Whatever paper box,paper bag ,envelope, folder, tag or another paper need to cut after printing. below are something about failures of paper cutter. hope it can help you.

1. There will be pressure oil in the oil filling hole on the top of the worm gear box or the lubricating oil height indicated by the worm gear box oil mark will increase significantly: this is mainly due to the damage of the polyurethane seal ring in the small oil cylinder, and the pressure oil has entered the worm gear box body As a result, the sealing ring must be replaced. The specific method is to remove the screw of the oil inlet pipe joint and two copper pads on the side of the small cylinder of the worm gear box, remove the fastening screws of the small cylinder and the worm gear box, remove the entire set of small cylinder, and then remove the back cover and spring of the small cylinder , Remove the piston to see the sealing ring. The small oil cylinder polyurethane sealing ring used in our series of paper cutters is divided into two types: shaft (installed on the inner wall of the small cylinder) and hole (installed on the outer diameter of the piston). Distinguish. During the installation, the Y-shaped opening of the seal ring should be oriented toward the inlet direction of the pressure oil, otherwise it will not work. In addition, when installing the small cylinder block, be careful not to drop the flat bearing on the push rod.

When replacing the polyurethane sealing ring, you must pay attention to the model, specifications, and date of delivery of the machine. Especially for the machines that have been shipped in recent years, the imported parts are used for the polyurethane sealing ring, such as the 1150 and 1370 specifications. The color of the polyurethane sealing ring is blue, and the size is 72 × 60 × 10mm, so please be sure to see the specifications and color of the original sealing ring when replacing.

The damage of the polyurethane seal ring of the small cylinder will also reduce the cutting force of the knife, and although the pressure of the sub-pump shows normal, it will not cut the paper. This is because the pressure oil cannot fully act on the piston of the small cylinder, and part of the leakage enters the worm gear box and causes pressure loss.

2. If the pressure oil output by the auxiliary pump can meet the requirements after measurement, but the knife cannot be lowered or the paper cannot be cut, it is likely that the cross on the push rod has been broken and the clutch disc cannot be driven.

The disassembly steps are as follows: place the knife holder at the lowest point, remove the end cover of the pulley (key 9), loosen the round nut and backwash washer on the worm, and pull out the entire pulley and bearing assembly with force. Then use the two screws on the clutch disc, use two small pressure plates to press the spring gland in the middle of the worm and the edge of the clutch disc, and tighten the two screws to disengage the spring gland and the shaft with the retaining ring. Circle, loosen the two pressure plates again, remove the spring gland and spring, and pull out the clutch disc to see the horizontal cross. (At the time of installation, care must be taken to insert the circular arc-shaped notch into the slotted notch of the push rod inside the worm).

In fact, to determine the reason why the paper cannot be cut after the knife is down, just simply try it as follows:

After the knife cuts to the pile of paper and stops, if you press the two-hand button again, the knife can continue to move until the end of a cycle, then it is basically certain that the hydraulic and mechanical parts are normal, and generally there will be no major problems. The reason for stopping is mostly because the alignment of the photoelectric protection is in a critical state, so the vibration when the knife is cut causes the deviation of the infrared emission and the received signal (similar to the fact that the photoelectric protection is blocked by the hand when the knife is cut); if again You can't continue cutting by pressing the two-handed button, so it is generally not related to the circuit, and you need to check the cutting pressure of the auxiliary pump or other mechanical reasons. [next]

3. If there is abnormal noise when the machine is idling, in addition to the noise caused by the quality of the double-connected vane pump itself, it is likely caused by the lack of oil or damage to the bearing in the middle of the pulley. The bearings at this place used paired bearings in the early stage. If oiling, both internal and external bearings must be taken into account. In addition, if the matching bearing cannot be purchased when replacing the bearing, an appropriate adjustment shim must be added according to the gap between the inner and outer ring planes of the two bearings (the wide faces of the outer rings of the two bearings are opposed when installing), neither can the bearing Crushing and hot can not cause the pulley to shake because the gap is too large.

Considering this problem, the machine pulleys that our company leaves now all use a single bearing (please pay attention when users replace and purchase).

If there is abnormal noise when cutting the knife: the mechanical reason is likely to be the damage of the bearings at both ends of the worm (especially the bearings near the small cylinder), which can be gradually disassembled in the order of (2) above until the worm is removed and the corresponding bearing is replaced (Note again: for safety reasons, if you want to remove the worm, you must put the knife to the bottom beforehand).

When replacing the flat bearing of the worm against the small cylinder, it must be noted that the upper and lower parts of the flat bearing have different inner holes. The small inner hole is installed on the push rod, and the large inner hole is installed on the small piston. Don't get it wrong.

The reason for the hydraulic pressure may be that the oil discharge pipe under the normally open solenoid valve in the hydraulic tank has fallen off, and the unloaded pressure oil is directly sprayed on the oil surface. The air foam splashed is drawn into the hydraulic line. When the cover plate on the front of the hydraulic tank is opened when the machine is turned on, it can be clearly seen that oil is sprayed down at the middle bottom of the valve plate. The oil pipe can be felt in the oil tank and screwed on, and then the air in the road can be discharged.

If there is air in the pipeline, there will be vibration when the paper presser presses against the work surface (more obvious when the pressure is large). The pressure relay pressure plate of the early model will continue to vibrate and cannot be knifed (note that now S Series models have eliminated the pressure relay component and replaced the time relay with a time relay to control the speed of the cutting knife after the paper is pressed tightly). To remove the air, place a wooden block about 6-7 cm high and about 50 cm long between the paper press and the workbench. Hold down the S12 travel switch on the left side of the fuel tank with your left hand. The spool of the valve causes the paper presser to slowly drop to the wooden block, and a little force is applied. This is repeated repeatedly until the noise becomes smaller and smaller, the air can be eliminated (you can also loosen the top side of the paper press cylinder at the same time) Hexagon head screw plug, so that oil and air are discharged together during the press of the paper presser and then tightened).

4. If the air in the pipeline often appears, it is necessary to consider whether the skeleton oil seal at the shaft head of the double vane pump is damaged. This seal is difficult to replace. Once the installation is not good, it will leak, and there is really no way to replace it. New oil pump. In the inspection, everyone should understand that the intake air of the hydraulic system must be the cause of the hydraulic oil input part. [next]

5. The cam behind the worm gear box moves clockwise when viewed from the bottom (viewed from the back). The correct position of the three travel switches and the cam during parking should be as shown in the component position diagram in the manual. The cam is about to leave; the roller of S5 stops on the left side of the small cam and cannot be held up (note: the S5 travel switch has been cancelled on S series models); S6 was just pressed by the cam). Their functions are as follows: the one on the left controls the normally closed solenoid valve in the hydraulic tank. When the platen presses down and the knife moves downward, the switch is turned off, and the normally closed solenoid valve is de-energized. At this time, even if the hands are released, the knife holder stops moving. Because the normally closed solenoid valve is closed, the pressure in the cylinder If the oil cannot flow back, the paper press will continue to press against the paper without lifting. The middle switch plays a single role through the small cam mounted on the large cam, which means that after each knife is cut, no matter whether you release your hands or not, the knife can only stop at the highest point and cannot work continuously. The switch on the right acts on the upper and lower half of the cycle, that is, during the process of cutting the knife, because the switch is in the off state, both hands must hold the button of both hands to hold the knife continuously. In the process of the knife seat lifting, the switch and the cam are closed and closed. By the control of the circuit, the knife can be automatically returned to the highest point when the knife is released. Sometimes a dead point occurs after the end of a cutting cycle, that is, the small cam in the middle fails to reach the right side of the S5 single switch roller but just bears on the single switch roller, so that it can no longer be carried out One cut. It is necessary to adjust the distance between the single switch and the upper and lower half switches to make the cam return to the correct state after each cut.

In the models of SQZK series, we have canceled the single switch of S5, and replaced the function of single down knife by the combination of S6 and S13, so that it will not appear because the knife seat is at the top dead center and can not continue Work this difficult problem.

6. If there is a small amount of sliding knife during the cutting process, loosen the hexagonal screw in the middle of the cam and turn the cam clockwise to a proper angle (the rotation angle can be adjusted gradually according to the actual situation. Note that the two cams must rotate simultaneously when adjusting). If the problem cannot be solved, you need to install a pressure gauge at the cutting force measurement point, and carefully observe whether the auxiliary pump pressure can return to zero immediately when the knife returns to the highest point. If you can not return to zero in time, it may be that the unloading is not smooth, you need to check whether the reset of the cutting solenoid valve is normal, and whether the oil path is clogged; if the pressure can return to zero quickly, it is likely that the piston of the small cylinder does not move Flexible, the strength of the clutch return spring is not enough, there are mechanical parts such as oil slip on the friction plate. In addition, the small oil cylinder can be removed to check several bearings at the end of the worm. If they are damaged, they will also cause the phenomenon of the sliding knife. Please remove them separately. Check the above parts.

7. Always pay attention to and adjust the gap between the pulley and the friction clutch. The specific method is shown in Figure 5. Loosen the four cylindrical head screws and tighten the other four hexagon socket screws to increase the gap. Otherwise, the gap will decrease. After adjustment, all screws must be tightened. The gap should be maintained between 0.5--1mm, and the gap is required to be substantially uniform throughout the circumference.