Common faults and troubleshooting of the hottest d

Common faults and troubleshooting of hot die casting machine

Abstract: This paper mainly summarizes the common faults and troubleshooting methods of hot die casting machine, for the reference of die casting workers

key words: die casting machine; Fault; Troubleshooting

because the hot die casting machine works under high temperature, high pressure and high speed, and the working conditions are relatively poor, after continuous long-time work, it is inevitable to have faults, such as abnormal noise, unstable action, and even the machine stops at a certain position and the cycle cannot continue. Once these faults occur, the operator should pay great attention to them, carefully observe them, judge the location and possible causes of the faults, and eliminate the faults in time to ensure normal production. For the general PLC controlled die casting machine, because there is no fault disclosure, it can only be judged according to the phenomena before and after the fault and the conditions required by the PLC control program, so it is more difficult to eliminate the fault; For the PC controlled die casting machine, due to its rich self diagnosis functions, i.e. fault disclosure and monitoring alarm functions, under normal circumstances, the alarm is related to the monitored parts, which is easier to diagnose and deal with. In short, once the die-casting machine breaks down, the operator or maintainer needs to make a comprehensive analysis in time, find out the cause and eliminate it

common faults of die-casting machine are: ineffective action, no action, no pressure, action error, etc. the key to eliminating these faults is to distinguish whether they are electrical, hydraulic or mechanical faults. Mastering the structure and working principle of the die-casting machine and the input and output conditions related to each action, the working principle of the hydraulic system of the die-casting machine and the pressure and speed adjustment methods are the basis for troubleshooting. Any abnormal sound, fastener looseness, part deformation and abnormal displacement need to be checked and repaired in time. The following focuses on the analysis and introduction of the possible causes and troubleshooting of 10 common faults of hot die casting machine

1 unable to lock the mold or automatically stop after locking for a period, unable to lock in place, able to open the mold

possible causes and troubleshooting

(1) the mold locking conditions are damaged

① the front or rear safety door is not closed

Troubleshooting: close the door or check whether the safety door is pressed in place? Is there any signal output or switch damaged

② no action of the mode locking oil valve

Troubleshooting: A. check whether there is signal output at each output point or whether the wiring is loose

b. check whether the relevant oil valves in the mold locking oil circuit, such as the mold locking oil valve, proportional valve, directional valve, etc., are stuck or whether the electromagnet coil is damaged

c. is the output pressure and flow (speed) normal

③ ejector pin does not return to its original position

Troubleshooting: check whether the adjustment of ejector stroke is too large and cannot be sensed? Is there no signal or damage to the proximity switch? Is the relevant oil valve in the ejector oil circuit ineffective or stuck

④ the manipulator does not return to its original position

Troubleshooting: check whether the proximity switch fails? Or the air valve doesn't work well? Stuck? When the pneumatic head is not used, the manipulator should be tied up to avoid loosening and false alarm caused by the drooping of the manipulator

⑤ mode-locked decoder parameter changes

Troubleshooting: A. check whether the mode-locked decoder has signal output or damage "All this starts from the A-pillar and cannot be counted?

b. is the gear and rack connected to the mode-locked decoder damaged or loose, or is the decoder support loose, resulting in inaccurate counting?

c. sudden power failure and shutdown cause the display value of the mode-locked decoder to change from the actual monitoring state, and it is necessary to readjust the original value of the decoder.

(2) Troubleshooting of low-pressure mold locking: A. check whether there is foreign matter in the mold or it is not closed well

b. whether the parameters related to low-pressure mode locking are set properly, such as low-pressure alarm time, pressure, position and other parameters

(3) the machine hinge, hinge edge and steel wire are seriously worn, and the movement to this part is stuck

Troubleshooting: replace the seriously worn parts

(4) there are foreign matters or wear and tear in the rear section of the mold locking cylinder, which block it

Troubleshooting: clean or replace

summary: in case of a fault, first use the alarm and inspection functions of the machine to determine the fault location. From the analysis of the relevant input and output conditions of the action, check the electrical control elements and contacts, check the control of hydraulic transmission, executive elements and components, check the parts and assembly status of mechanical parts, find out the cause of the fault and eliminate it

2 possible causes and troubleshooting of unable to open the mold or open the mold:

(1) relevant conditions of mold opening are damaged

① no action of mold opening oil valve

Troubleshooting: A. check whether there is signal output at each output point or whether the wiring position is loose

b. check whether the relevant oil valve in the mold opening oil circuit is stuck or whether the solenoid coil is damaged

c. is the corresponding output pressure and flow (speed) of mold opening action correct

② ejection cylinder not returning

Troubleshooting: refer to the inspection method of ejection cylinder not returning to the hammer for troubleshooting

③ inaccurate counting caused by changes in the parameters of the mode-locked decoder

Troubleshooting: refer to the relevant parts of mode-locked troubleshooting

(2) the installation mold is not adjusted according to the operation requirements, the mold locking is too tight, and the mold locking downtime is too long

(3) the mold does not re adjust the volume modulus after the temperature rise and expansion, resulting in the increase of the mold locking force, and the difficulty of mold opening

analysis: the mold cannot be opened. After eliminating the failure causes caused by the destruction of mold opening related conditions, we should focus on whether it is affected by improper mold adjustment, too tight mold locking, too long mold locking time, mold temperature and other factors? As shown in Figure 1, because the thickness of the die is different, the die-casting machine using machine hinge die locking is adjusted by the mold adjusting mechanism. First adjust the mold space, and then adjust the clamping force. When the hinge is almost straight（ α＞ 0), the mold is just closed, and the clamping force is zero at this time; Further mold locking, when the machine hinge is fully extended（ α＝ 0), generate the maximum clamping force and self lock. After the mold locking cylinder, the machine hinge will compress the mold e, and the Colin column (pull rod) will be elongated f (both should be within its elastic range). At this time, if the mold locking is too tight and the mold locking time is too long, the lubricating oil at the machine hinge is extruded. Under the static pressure generated by the mold locking and the dry friction state without lubrication, the speed and pressure of mold opening for a period of time are often insufficient to open the mold. On the other hand, when the mold is heated and expanded, the deformation of thermal expansion leads to the additional increase of clamping force, resulting in the failure of difficult mold opening

Troubleshooting:

check the mandrel ① check and eliminate the faults caused by the conditions related to mold opening

② increase the pressure and speed of mold opening for a period of time. After lubrication, reopen the mold in the manual state

③ increase the system pressure within the rated pressure of the system, and restore the original system pressure and corresponding parameters after opening the mold manually

④ the mold adjustment is carried out under no-load condition. When the above two methods do not work, only loosen the front coring column nut of the head plate, loosen the mold, reinstall the nut, and adjust the parallelism between the moving and fixed plates. Do not try to use the mold adjusting mechanism to forcibly open the mold in the mode locking state, otherwise it will cause unnecessary damage to the mold locking mechanism, such as breaking the chain, damaging the sprocket, and even damaging the mold adjusting motor

⑤ adjust the mold holding space and mold locking force in strict accordance with the mold adjustment steps. When the mold is installed and tested for a period of time, the mold temperature rises and expands, and the mold locking force increases, pay attention to adjust the plastic modulus in time, so that the mold locking force returns to the original value, so as to avoid mold opening failure

⑥ reduce the mold locking downtime. Remember to open the mold before shutdown, and never stop the machine when the mold is locked

(4) elbow bar (or elbow) mechanism 1 under general conditions, the parts are seriously worn or damaged

Troubleshooting: replace the parts that are seriously worn or damaged

3 flying material

flying material occurs from time to time in production. Once flying material occurs, stop the machine immediately for inspection, find out the cause and solve it before continuing production. Location and possible causes of flying material:

(1) flying material at the joint of nozzle body and gooseneck

① there is a deviation between the center of mold inlet and the center of nozzle. After working for a period of time, due to repeated impact, the joint of nozzle body and gooseneck is loose and flying material

exclusion: reset the center. It is suggested that a locating ring consistent with the pre perforation of the head plate should be added in the mold design

② manufacturing quality problems. The nozzle body does not fit well with the gooseneck cone, resulting in flying materials

Troubleshooting: remove the nozzle body, clean the zinc material on the taper surface of the nozzle body first, then clean the zinc material on the inner surface of the gooseneck taper hole, properly grind and match the two matching conical surfaces, and then reinstall the nozzle body. If there is a top bottom phenomenon, the end of the nozzle body should be properly cut off and then ground

③ incorrect installation method of nozzle body leads to poor cone fit and flying materials

Troubleshooting: the correct installation method is to heat the gooseneck conical hole to a certain temperature (about 300 ℃), and then tightly sleeve the nozzle body into the conical hole. Insufficient heating temperature or normal temperature installation will lead to loose fitting cone and flying materials during high-temperature operation

(2) flying material at the joint of nozzle and mold inlet

① there is deviation between the mold inlet and the center of nozzle, and it is not aligned

exclusion: reset the center

② the mold inlet is inconsistent with the gooseneck nozzle; The inlet angle, roundness and size of the hole may not match

Troubleshooting: trim the water inlet of the mold or replace the nozzle. When processing the mold inlet and nozzle, it should be made according to the standard

③ insufficient nozzle force during shooting

Troubleshooting: check and eliminate the failure of the nozzle oil circuit, and appropriately increase the nozzle force

④ after leaving the mouth, there is zinc dripping at the head of the nozzle

elimination: clean up the dripping zinc liquid, appropriately extend the delay time from the mouth or try to improve the cooling conditions at the water inlet

(3) flying material at the mold parting surface

① the mold holding position is not adjusted properly, and the mold is not locked

Troubleshooting: readjust the clamping force

② the machine hinge is seriously worn, which reduces the clamping force of the formwork

Troubleshooting: replace or repair the severely worn parts of the machine hinge

③ the parallelism of the mold itself is not good or the mold is seriously worn after repeated use

exclude: repair the mold

④ the parallelism between moving and fixed plates is not adjusted well or there is deviation after use

elimination: readjust and fix the parallelism between plates to meet the requirements

4 hammer head stuck

analysis: the hammer head and the driver are manufactured at room temperature, and the matching gap is about 0.15mm. When working at about 410 ℃, the outer diameter of the hammer head will expand due to temperature rise and thermal expansion, while the driver and the gooseneck have a small expansion trend due to wall thickness. Under high temperature working conditions, the working gap between the hammer head and the driver is only about 0.03 ~ 0.06mm. If the temperature is too high (above 450 ℃), the gap between the hammer head and the driver cylinder will be further reduced, so that the gap fit will change into an interference fit, and the hammer head will be stuck. Therefore, the possible causes of hammer head jamming are:

(1) high pressure chamber and furnace temperature lead to hammer head jamming

prevention method: strictly control the material temperature. There are several reasons for the material temperature out of control: ① thermocouple ② thermostat ③ combustor. Failure in any of the three aspects will cause the material temperature to be out of control, so the material temperature should be judged according to the surface condition of molten zinc during die casting; Remove the scum on the surface of the molten zinc. If the liquid level is clear, silvery white, without iron branches, and the surface is relatively slow to oxidize and slag, it indicates that the material temperature is appropriate; If the liquid level is dark red and the surface oxidizes and slags quickly, it indicates that the furnace temperature is too high, or use a portable thermometer to re measure the material temperature. When it is found that the temperature exceeds 430 ℃, the reasons for the high temperature should be found from the above three aspects and eliminated

(2) there is too much dross on the zinc level in the crucible and the liquid level is too low

elimination: remove the dross and add zinc material in time to ensure that the liquid level is not less than 1 inch below the surface of the crucible

(3) machine