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maintenance of machine

maintenance of injection molding machine

   In order to ensure the machine work normally,lower trouble and prolong the using life of machine ,user must note to maintain the machine during everyday use.

7.1 daily check

No.1:check to see if the button of emergency stop is normal:

No.2: check to see if there is abnormal noise during machine running :

No.3:check to see if the mechanical ,electrical and hydraulic safety device is normal ,do the movement of clamping mold by operation style of manual ,semiautomatic and automatic separately,open the safety door to be 20-30mm to test whether the movement of clamping mold can be stopped:

No.4:check to see if the oil position in hydraulic tank is over the middle position in hydraulic pressure gauge and whether leak:

No.5:check to see if the grease/oil is enough on lubricating equipment and lubricating spots,to see if the liquid position of lubricating pump is enough high

No.6:check to see if the work pressure of hydraulic system is too high

No.7:check to see if the oil temperature is increasing too fast and the water supply for cooling is normal

No.8: check to see if the heating to screw barrel is normal and the running of temperature-controller is normal

No.9:check to see if the mold installation is steady

No.10: check to see if the mold installation is steady

No.11:check to see if each parameter set of injecting is right

 

7.2 Periodic check

  7.2.1 check weekly

1do routine check according to above 7.1

2check to see if the wire connection of each limit switch ,heater band and thermocouple and screw is loosened or broken off .

3check to see if there is phenomena of leaking oil for the hydraulic cylinder ,joint ,flange and soft pipe, if that ,replace correlative airproof ring

Specification of bolt

Moment of forceskg*m

M3

0.23

M4

0.46

M5

0.92

M6

1.6

M8

3.9

M10

7.5

M12

13.0

M16

30.6

M18

43.0

M20

61.6

M24

80.4

7.2.2 check monthly

1do routine check according to above details

2check the tightening screw and nut of each structure to see whether it is loosened, if that,tighten it ,as to details of tightening bolt:refer to the right table shown

3check the net-shape filter to see if there is filament or other granule jammed it ,clean off it if necessary

4check to see it is corrosive in the inner of coolre for oil and the external of heat conductor pipeif supply water by city ,check it every six months ,then to see if it need cleaning off

 

7.2.3 cheak yearly

1do routine check according to above details

2check to see if the hydraulic oil is degeneration and polluted ,replace new hydraulic oil if necessary

3check to see if the wire is aging and ossify ,if that ,replace them

4check the screw .screw collar .collar seat and mixing head to see if they are worn

5check the charging motor to see if there is noise when the motor running ,if the earing of rotation shaft has been damaged ,replace it

6clean off the whole machine ,clean off the oil dirt on the surface

 

7.3 maintenance of cooler for oil

   This machine adopts cooler for oil with floating pipe style to cool the hydraulic oil .the water for cooling to into the lid’s cavity for water entering-and-going through the coming connection pipe,then flow along with the cooling pipe.the flowing water absorbs the heat which is sent out by the hydraulic oil then to out through the exit connection piperefer to the following drawing

   The cooler for oil works for a long time .the water medium is accumulated gradually on the wall of cooler ,which will decrease the performance of emitting heat ,so it can’t ensure to reach the requirement of oil cooling ,when you should inspect and maintain the cooler for oil .

 

7.3.1 steps of inspection and maintenance

No.1.close the valve of mouth of oil coming-and-going and water coming-and-going .give out te left water in cooler ,then discharge it from machine

No.2.loose the screw on the lid for water entering-and-going,and discharge the entering-and-going water lid.take down the airproof washer at the same time

No.3 loosen the screw on back lid ,discharge the back lid ,take down the airproof ring at the same time ,draw out the cooling equipment from the end of position hole

No.4 lead clear water througt soft pipe to lid for water entering-and –going and clean it,clean off accumulated dirt in back lid and inner wall of pipe for cooling ,wash inner wall of pipe for cooling with soft cloth.

No,5 use alkalescent wash which can be got from market ,wash the inner wall of pipe for cooling again ,the washing pressure can’t be over 5kgf/cm2,watching the water flowing from the pipe during washing ,the cleaning work is finished until clean water flowing out of pipe

No.6 as to the sandwich dirt which is difficult to clean,use weak muriatic acid liquor dipping in it for 15-20minutes ,until the liquor flowing out is near same as clean color;

Notice:

If using wash to clean it ,must clean it with clean water repeated to avoid chemical substance in wash eroding it.

No.7 after clean it with clean water,blow to dry it by compressed air at last.

No.8 assemble the all parts in order ,there can’t be phenomena of distorting for each airproof ring when assembling .

No.9 do test of water pressure ,fill water fully to the place where the water for cooling go by in cooler,then close the mouth of oil coming-and-going ,fill compressed air 5kgf/cm from the mouth of ejecting air of oil side , when the mouth of ejecting air of water side should be open state ,if there is leakage phenomena,the water will overflow form the mouth of ejecting air of water side

No.10 after finish test ,assemble the machine as its origimal sample,and connect pipeline well ,

 

7.3.2 Notice during using cooler for oil

   1.medium for cooling is clean fresh water ,match water filter if the water quality is bad explain to manufacturer if using seawater for cooling

2. in cold reason,must give out left oil and left water to avoid freezing if not use it for a long time.

3.the temperature of water for cooling should be low and the flux of water should be big in order to avoid forming water dirt ,if the water supply for cooling come from under ground water or industrial water or other water with many salt-alkali element.which will cause water dirt to from in cooler more fast

4.give out air periodically ,do periodic inspection and washing to the interior ,the washing period is up to the water quality: the maintaining period is about six months if water supply is from city,while the maintaining period is one month if water supply is from water under ground or industrial water

5.Note the tempreature of oil coming or going when working ,adjust the temperature of oil going through adjusting the coming flux of water for cooling so that make it meet the requirement.

 

7.4 maintenance of net-shape filter

   Net-shape filter has function of filtrating oil .the oil pump absorbs clean oil so that the hydraulic system of machine can run normally, after the machine running for a long time, the oil cycles continuously,the surface of net-shape filter will adhere impurity in oil ,even be jammed by the impurity ,which will influence the oil pump to work seriously .so it is very important to inspect and clean the net-shape filter periodic.

   In the first year using machine, inspect and clean it every six mouth,later inspect and clean it every year when replace oil .

 

Steps of machine:

   No.1 discharge the cover of oil tank ,give out the hydraulic oil in the oil tank completely.screw off the net-shape filter from the pipe oil coming in oil tank

 

No.2 clean oil tank thoroughly

No.3 clean the filter with gasoline or coal oil ,and clean filament or thin granule which is adhered on the surface of filter thoroughly

No.4 if find net-shape filter is damaged ,must replace a new one.

 

Notece:

mustn’t scrape the net on surface of filter with rigidity substance to avoid damaging net

when discharging the oil filter ,mustn’t start motor of hydraulic pump

after install the filter and when starting motor of hydraulic pump ,let the motor of hydrculic pump run for ten minutes without loading ,check it to be normal then it can work with loading

 

 

7.5 clean and inspect the screw and screw barrel

   Adopt the way of exchanging plastic whose flowing performance is good to clean screw barrel ,and should follow right operation steps when exchanging plastic:master technical data such as the heat stability of plastic,forming temperature range of plastic and consistency with other plastic,etc,if the forming temperature of plastic with good flowing performance is much higher than temperature of plastic in screw barrel.first,increase the temperature of screw barrel and nozzl to be the lowest processing temperature of plastic with good flowing performance ,then put plastic with good flowing performance into the screw barrel ,and inject it for nothing continuously until clean out all after plastic in screw barrel ,adjust the temperature to be normal to produce at last,if the forming temperature of plastic with good flowing performance is much lower than temperature of plastic in screw barrel , first ,increase the temperature of screw barrel and nozzle to be the best flowing temperature ,then cut off electric power for heating ,clean screw barrel using plastic with good flowiing performance at the condition of lowering temperature ,if the forming temperature of plastic with good flowing performance is hihh,and melting mucosity is big ,moreover ,the plastic in screw barrel is material which is sensitive to heatsuch as PVCyou should choose polystyrene with good flowing performance and high heat-stability or polyethylene with low density as transition material in order to avoid plastic be decomposed,

 

7.5.1 discharge the screw and screw barrel

The screw and screw barrel are important components of molding parts ,the screw, screw barrel ,screw head and screw collar maybe will be worn or scraped when the machine run for a long time or using reclaimed material often to mold, so discharge the screw and screw barrel to check and clean if necessary ,and to see the degree of wearing and scraping .

A: preparations befor dischanging

if the left plastic in screw barrel is material with high viscosity and be sensitive to heat such as PVC,PCetc,the plastic will be stick in the surface of screw and inner hole of screw barrel after it is cooled,when peel off it ,must be care of maybe damage the metal surface ,must clean the screw barrel and screw according to the way shown in above section 7.5 before discharging them.first put plastic with good flowing performance into the screw barrel ,and inject it for noting continuously until clean out all left plastic in screw barrel :

prepare flowing assistant tools or material :

a:four or five wooden stick or steel stickdiameterdiameter of screw,lengthstork of injecting

b:four or five segment square-shape hardwood

c:clamp

d:several piece of waste cotton or waste cloth

e;one piece of waste cotton or waste cloth

f:fireproofing flux

g:brass stick or brass brush

moving position of whole injection base

NO. 1 start motor of oil pump

No.2 adjust the baffle for limit switch of base back to be max ,position

No.3 press the button of “base back “and make the injecting equipment back to the bottom position

No.4 discharge the bolt between the base of injecting and base of flange for oil cylinder which charges the whole movement of coming-and-going,make them separate,

No.5 take out inner hexagon screw on front and back supporting of injecting device .loosen the screw for adjecting

No,6 turn the whole injecting base at a angle .and push it to the direction of operation,as shown in following drawing

B:steps of discharging screw

No.1 heat the nozzle of screw barrel and make its temperature to be the max ,value of melting temperature of plastic in screw barrel, then cut the heating power supply

No.2 adjust each injecting pressure and injecting speed to be least value in computer

No.3 start motor of oil pump ,make it to be manually-operation state,press the putton of “charging” injecting piston back to limit position of stroke

No.4 discharge following parts in order:heater band for nozzle→nozzle→front body of screw barrel.as shown in following drawing

No.5 discharge following parts in order:screw→half ring→pull out end of screw→screw for fixing→pin.as shown in following drawing

No.6: take a segment of hardwood and put it at the end of screw ,clamp the hardwood with clamp,start the motor of oil pump, make it to be manually-operation state, press the button of “inject”to push the hardwood and screw to the front of screw barrel. When reach the limit position of injectig stroke,press the button of

No,7 add second segment of hardwood,repeat the movement of above No6,so that push out the screw from the front of screw barrel gradually.

Notice:

   Mustn’t push out the screw by hand directly because the screw hasn’t cooled at this time ,after discharge the screw ,put it on wood to avoid burr.

C:steps and way of discharging screw barrel

No.1 discharge all the heater bands and thermocouple on screw barrel

No.2 turn whole injecting base ,let it to be original position and tighten it with screw

No.3 loosen and dischrge the notch nut which is fixesd the end of screw barrel

No.4 lift the screw barrel for the moment with lifting deviceNote the center of gravity﹚﹙refer to following drawing

No.5 as shown on above drawing ,take a segment of hardwood and put it between the base of charging and end of screw barrel ,clamp the hardwood with clamp,start motor of oil pump ,press the button of “injecting plastic”.make the base of charging push the hardwood along with screw barrel out

No,6 back the base of charging ,use another hardwood to repeat the step above No,5 until push screw barrel out of injecting base ,at the same time,concert the movement of screw barrel with lifting so that make the screw barrel level

No,7after discharge the screw barrel .put away it on safety place

 

7.5.2 clean screw and screw barrel

A:clean and inspect screwas shown in following drawing

No.1 cover the screw handle on the end of screwside with key slotclamp the screw head,rotate the screw out as shown on above drawing,screw head is left-rotating screw

No.2 wipe the main body of screw with waste cloth or cotton and clean off the colopyony deposit on the surface

No.3 heat the surface of screw evenly with coal oil light ,then scrape it with waste cloth or cotton ,clean off the deposit on surface of screw with brass

No.4 clean the components of screw head ,screw collar,collar seat and mixing head according to above way of cleaning screw surfaceas shown in following drawing

No.5 wipe off all oil dirt after cooling

Notice:※

A :mustn’t clean the deposit on screw by scraper ,grinding wheel or iron stick forcibly to avoid damaging smooth surface of screw

B : when install screw head ,put some silicon oil or disulphide molybdenum lubricate grease to avoid them joint,only thin layer is enough or will dirty plastic product the grease is too much

No.6:check the inner or external screw thread of screw ,screw head and mixing head to see if it is damaged .if that ,there will be trouble such as countercurrent when injecting mold,or measurement fluctuating ,etc.

B:clean and nspect screw barrel

No.1 clean off the colophony deposit on surface of screw barrel when the screw barrel remains some heat

No,2 slip waste cotton into the inner hole of screw barrel ,push the cotton come-and-go to clean the inner surface of screw barrel

No.3 heat the nozzle and front parts of screw barrel by coal oil light clean the external surface .screw thread and each contact surfaceas shown in following drawing

Notice:

  Wipe each contace surface shown above drawing carefully to avoid burr or scraping ,or scraping,or will cause leakage when molding

 No,4 if there is left deposit on the inner surface of screw barre; ,use waste cotton dipped with trichloro ethylene to clean it

No,5 finish clean work ,dry the surface ,check to see if the inner surface of screw barrel is worn or scraped

7.6 elininate common problems

7.6.1 the motor of oil pump doesn’t work

(1)if the motor of oil pump doesn’t work ,and there is unusual noise ,check to see if the fuse has broken or been fused,then check to see whether the three-phase electric power supply is normal .

(2)if the motor stop suddenly ,to see if the air switch is in over condition ,close the air switch after two minutes ,start motor of oil pump

(3)if having pressed the button of “start motor”,while the motor doesn’t work ,to see if the button has been damaged or the heat replay is breaking off ,at the  some time .check the emergency button or other correlative wire connection

(4)the oil pump is jammed so that the motor can’t work ,when you shoule discharge and clean the oil pump and take out of foreign substance ,then check the rotation space of pump’s vane

(5)the motor is burned ,then you should repair or replace the motor

7.6.2 the motor can work ,but it can’t engender pressure

(1)the electromagnetic iron wire ring of presure proportion balve doesn’t adsorb or the core of valve is jammed by sundries ,when should discharge to clean it .at the same time check the electromagnetic iron wire ring to see if it is burned or the connection wire is loosened

(2)the hydraulic oil is not clean,leak oil because of motor wearing after the motor was used for a long time ,repair of replace the oil pump

(3) the hydraulic oil is not clean ,the sundries is accumulated on the surface of net-shape filter so that disturb the oil go into the oil pump.when you should clean the filter and replace hydraulic oil

(4)to see if the motor is in reverse condition

(5) to see if the pressure gauge is bad,if that ,replace it .

 Notice:

      If the oil pump has been discharged to repair ,must assemble the components in it according to their original position,otherwise the oil pump maybe assembled at inverted direction ,if that,even if the rotation direction of motor is right,pressure can’t be engendered

7.6.3 the movement of clamping mold doesn’t work

(1) to see if the safety door is closed,or the connection wire of limit switch on safety door is loosened or is damaged

(2) to see the ejector mandril backing does’t reach the required position or the linear displacement transducer is no use ,adjust the set of ejector mandril position or check the linear displacement transducer

(3) the wire of hydraulic valve for opening mold and clamping mold is burned or maybe the core of valve is jammed by sundries ,clean or replace it

(4) the airproof of piston on clamp cylinder doesn’t work

 

7.6.4 the movement of locking mold doesn’t work

(1) to see if the position setting of linear displacement transducer used when finish movement of clamping mold in low pressure and change to locking mold in high pressure is right ,or reset the position

(2)to see if the force of locking mould is enough

(3)to see if the mold is adjusted too close ,if that ,increase thickness of holding mold

7.6.5 Not inject

(1) to see if the wire of hydraulic valve for injecting is burned or the core of valve is jammed by sundries ,clean or replace it

(2) to see if the heating temperature for screw barrel is too low. Note the alarm from computer,check the heater band or fuse ,adjust the temperature setting in computer

(3)check the allowed temperature tolerance of temperature setting in computer

(4)to see if the approach switch for injecting base forward isn’t connected or the connection wire is broken ,adjust the position of baffle and check the approach switch

(5)to see if the limit switch of protecting cover for injecting head isn’t connected.

 

7.6.6 the screw doesn’t rotate

(1)to see if the wire of hydraulic valve for controlling charge is burned or the core of valve is jammed by sundries,clean or replace it

(2)the hydraulic temperature is too low the computer stops automatically and alarms

(3) to see if motor for oil pump is over loading ,if that ,stop the movement of charging immediately to avoid damage the screw ,and check to see jif the motor is damaged

(4) there maybe be sundries going into the screw barrel when charging ,which make the screw occlude screw barrel

(5) the position setting for stopping charging isn’t suitable ,reset it

7.6.7 the screw can rotate,but not charging or the speed of charging is slow

(1)the screw barrel isn’t connected with water for cooling or the water for cooling isn’t enough so that the temperature of fallen plastic go up ,which prevent the plastic going so take out the agglomeration plastic which is melt

(2) to see if there isn’t plastic in hopper

(3)the adjustment of adjusting valve for back pressure isn’t suitable or there is sundries to jam it in valve ,the back pressure is too high so that make the screw back off slowly

(4)sundries go into the screw barrel so that it isn’t smooth for plastic going

 

7.6.8 the screw rotates abnormality and quantity of injecting isn’t stable when injecting

(1)the injecting components ,especially the screw collar is damaged ,so that make the melt plastic regurgitate ,which lead the screw rotate

(3)the screw barrel or screw has been damaged

 

7.6.9 movement of adjusting mold doesn’t work

(1) to see if the select switch isn’t in state of “on”(the indicating lamp isn’t light)

(2)wire of electromagnetic commutating valve for adjusting mold is burned, or there is sundries to jam it in valve.clean or replace electromagnetic valve

 

(3) to see if the parallet of molding platen meet the requirement ,see if the level position of machine frame is wrong ,which will bargen the movement resistance of molding platen

(4)to see if the motor of oil pump is damaged

(5)check the work pressure.

 

7.6.10 the movement of opening mould isn’t sensitive or there it engender noise

(1) check to see if the position setting for finish opening mold is suitable

(2)wire of electromagnetic commutating valve for opening mold is burned, or there is sundries to jam it in valve ,clean or replace electromagnetic valve

(3) check the work pressure ,increase the pressure suitable

(4)the position setting for finish opening mold isn’t suitable ,which will make the piston strike the back cover of oil cylinder ,reset the position to be suitable

 

7.6.11  the semiautomatic operation doesn’t work

   The semiautomatic operation is realized through electric signal which is sent by computer controlling each electromagnetic valve.if each movement is normal in manually-operation state.while the semiautomatic operation doesn’t work ,whose reason mainly is electrical limit switch or approach switch of time-relay doesn’t send out signal ,or the wire connection is loosed or broken ,way of finding problem.firstly,look at the semiautomatic movement to find which phase doesn’t work ,then contrapose the drawing of electrical principle to find out the correlative controlling components or wire,inspect them and solve the problem